Oan Energy Conduit: The rings use Oan energy (supplied by a Green Lantern Power Battery) which in most cases takes the form of green light. Rot Lop Fan, from a race without eyes, perceives it as the sound "F-Sharp" and his 'ring' is actually a bell. A Green Lantern's ring, considered to be one of, if not the most powerful weapon in the universe, has the ability to affect and use fundamental forces of the known universe, including gravity, radiation, heat, light, and blasts of concussive force. It is also theorized that the ring also has a basis in other dimensional energies commonly called magic by users of such energies. The ring can also create fields of force formed from an unknown energy that was bound by the users' will. The limitations of such use are the skill, knowledge and imagination of the user.
Energy Projection: The ring can be used to fire blasts of Oan energy or create weapons such as projectiles of them. The ring can project beams of force powered by the will of the user. Kyle generally uses fanciful constructs in the shape of advanced technology. Their appearance does not indicate the power of the weapon. The weapons power is more an indication of the will of the user. Certain users (i.e. Hal Jordan) have been powerful enough to stagger even Superman. If the user wishes, they can alter the form of the blasts, such as Kilowog's "booms."
Force Field: The ring can create various forcefields of various sizes and shapes to protect the wearer and others around him. With the cosmic scope of a Green Lantern's duties, it is only natural that the power ring is designed for operation in space. The ring creates a force-field around the wearer, protecting him/her/it from the hazards of the void including filtration of stellar radiation and microscopic particulate matter which would ordinarily be fatal should the space debris strike the ring wielder at high speeds. An atmosphere appropriate to the ring wielder's biology is created inside the force-field, body temperature is maintained and waste products are removed. Gravitational stresses which could cause injury are stabilized for the ring wielder. The only exception to force fields was attacks based on the color yellow. The newer version of the ring is not limited by the color yellow as long as the wielder can overcome their fear.
Energy Constructs: The ring can form constructs of Oan energy. The primary function of the Power Ring is to provide a weapon capable of transforming the wearer's thoughts into physical constructs through the wearer's strength of willpower. A Green Lantern can create any particular items or construct that they can imagine as long as they have the willpower necessary to will it into existence. The constructs are made out of green energy, which is a tangible form of pure willpower, and they exist only as long as a Green Lantern is fueling it with their willpower. Items created by the rings are not indestructible and are only as powerful as the willpower of the Green Lantern creating them. The types of constructs usually reflects the ring wearer's personality. Green Kryptonite has also been constructed using a Ring.
Phasing: The Power Ring allows the wearer to pass through certain solid objects, such as walls. Which objects that are not penetrable are not known, but it may depend upon the strength of the wearer's willpower and the density of the object's molecular structure. It has also been cited that the wielder could pass through the fourth dimensional gap or dissemble their own molecular structure.
Environmental Playback: Upon request, the power ring can recreate a holographic environment based on data in its memory banks. The ring wielder can observe events in a ghostlike state, but the ring wielder cannot alter the outcome of the playback. All objects in the playback will appear in the full spectrum of colors, regardless of the wielder's level of expertise creating simulacrums. The power ring will automatically end the playback if outside interference warrants the ring wielder's undivided attention.
Invisibility & Light Refraction: A ring wielder can render him/her/itself invisible by willing the ring to bend light waves around his/her/its form, as well as that of the power ring. Presumably, a similar action allows an experienced ring wielder to create objects of colors other than green. As Hal Jordan's experience grew, he was able to create power ring illusions of people and objects. It can be assumed the ring wielder would not risk the extra time and effort to create other colors in a combat situation.
Energy Twin: The power ring allows the wearer to create an "energy twin" of his/her/itself that can travel at far greater speeds than that of the ring wielder's physical form. While the energy twin is active the ring wielder remains motionless, his/her/its life force is needed to guide the energy twin. The energy twin can not alter its surroundings, and may only be perceived by the Guardians or another ring wielder as a green, ghostlike image. Any knowledge gained by the energy twin is transferred back to the ring wielder's physical form upon recontact with the body. The Guardians frequently used energy twins as a means of contacting a Green Lantern. As a rule, a ring wielder can not create actual, independent duplicates of him/her/itself, as the power ring cannot create life.
Energy Absorption: The ring can absorb and store most other energies. Doing so does NOT replenish the normal store of energy the ring has. A ring that needs recharging but contained a store of electricity could only discharge that electricity, for example. In an episode of Static Shock, John Stewart was able to defeat Sinestro via merging the remainder of his Oan energy and discharging it simultaneously with electrical energy supplied continuously by Static.
Flight: By the manipulation of anti-gravitons and directed molecular movement, the ring allows the user to fly at incredible speeds. In atmosphere, a Green Lantern has been known to fly as fast as Mach 10 in atmosphere by creating an aerodynamic envelope around his body. Towing others, usually within a bubble, his speed is limited to the twice the speed of sound or 1440 mph. In space, Green Lantern's speed can be significantly greater and has been known to approach 80% of lightspeed in normal space. Flight is possible at velocities exceeding light speed. In atmospheres, air friction is not a hindrance, since heat is either absorbed or reflected by the ring's field.
Wormholes & Spacial Warps: The power ring grants its wearer access to wormholes in space, enabling the ring wielder to rapidly cut time and distance needed for transport. The Guardians established at least one known wormhole to Oa, which required the use of a power ring to enter. Black holes can be navigated by experienced ring wielders. During a battle with Sinestro and his ally, Mad God Sector 3600, members of the Green Lantern Corps of Earth and the Green Lantern Corps of the Klyminade traveled through a black hole to be deposited outside a white hole in Space Sector 872. The power ring cannot generate a Boom Tube, as it needs a Mother Box and a sample of the highly unstable X-Element. There is no known way to duplicate either item, even with the power ring. Should a Green Lantern make his/her/its way to the other-dimensional worlds of Apokolips or New Genesis through a Boom Tube, the ring will function as it does in the rest of the universe. John Stewart encountered no ring related difficulties during his stay on New Genesis, despite the loss of the
Central Power Battery. The ring wielder would still need a Boom Tube to return to his/her/it's dimension.
Time Travel: Time travel is possible with the power ring, though the further forward in time a ring wielder travels, the more willpower it takes. As Green Lantern, Hal Jordan once explored as far as the 70th century. Jordan had also traveled to the 58th century as Pol Manning, a role later adopted by Salaak of Slyggia.
Limited Cellular Regeneration: This ring has a limited ability to heal physical injuries; this seems to be a feature held over from the previous incarnations of the ring. Green Lantern can use the ring to repair minor injuries in himself or others. Speculation has been rendered to wonder if Kyle actually had medical knowledge, that he would be able to cure a wider variety of dysfunctions, beyond normal physical injuries.
Electromagnetic Scanning: The ring has a wide range of detection abilities based on the imagination of the user. If one can conceive of it, he can probably detect it. Magical effects like clairvoyance, seem to be beyond the scope of the ring. Most normal electromagnetic phenomena are within the range of the ring, including radio, television, infrared, ultraviolet, and high frequency band communications.
Search Probes: A user was capable of sending probes through their Power Ring that were tasked with locating specific targets or individuals.
Galactic Encyclopedia: The earlier rings worn by the Corps functioned as references for their users. Having the vast knowledge of the Oans to draw upon, each ring functioned as a ready reference on most peoples, stellar events and conditions that may have been seen by other rings or other Green Lanterns. The rings also served as a repository of adventures had by the Green Lantern and these mission reports were stored in the Prime Battery on Oa for review and training.
Universal Translator: The power ring can translate virtually any language in the universe, facilitating diplomatic encounters rather than violent confrontations. Complications can arise, though, when a frame of reference for translation is not available, as evidenced during Katma Tui's induction of Rot Lop Fan into the Green Lantern Corps.
Material Alteration: The Green Lantern's uniform is not made out of fabric. It is created by the Power Ring whenever the wearer wills to wear it. It automatically appears over the wearer's normal clothing, and vanishes when the wearer wills to return to their civilian attire. Most Green Lanterns wear similar uniforms that are programmed into the ring by default, such as Hal Jordan's uniform. However, each Green Lantern is able to adjust their uniform to fit their own needs, personalities and whims. Jack Chance is the most extreme example, refusing to wear a uniform save for a Lantern badge on his trench coat. The green parts of the wearer's uniform are usually hot to those who touch it, while the black parts are cold. The uniform also produces a "siren" taking on the form of the Green Lantern Corps' symbol, circling the Green Lantern when active. The symbol, or badge, will not appear on the uniform until after a newly inducted Lantern has completed training on Oa, leading to the term "White-circle" to describe a rookie Lantern.
Ring Duplication: Most Power Rings are capable of automatically duplicating themselves. Each duplicate typically shares the qualities and capabilities of the original ring. Each duplicate still requires to be recharged by a personal power battery. Some "temporary" rings can also be made, as well as rings with severe limitations and pre-programmed commands. All power rings, as being based upon the green ring templates created by the Guardians of the Universe, are all programmed to be able to duplicate themselves on a specialised command known apparently only by the Guardians.
Emergency Beacon: A Green Lantern in distress can use his/her/its power ring as an emergency beacon. The alert can be directed to a Green Lantern's neighboring sector, or it can be a Corps-wide alert.
Homing Beacon: A homing beacon in the power ring can lead one Green Lantern to another. This was one of the recent power ring upgrade features added by the Guardians of the Universe. The power ring can be ordered to disguise itself to elude power ring wielding trackers. Most often ring wielders will allow the beacon to signal their location to others. The Green Lantern Corps of Earth found the remnants of the Green Lantern Corps of The Klyminade by tracking them through their power rings.
Mind Alteration: Though the ethics of mind tampering may be debatable, sometimes it is necessary. As the power ring relies on thought and will to operate, mind tampering is not impossible. The difficulty lies in properly applying the power. There lies a risk of catastrophic damage to the mind should mistakes be made. A ring wielder can use the power ring to erase portions of an individual's memories. To protect his secret identity as Hal Jordan, Green Lantern created a mental block in the mind of Major Disaster. Green Lanterns have used mind techniques as part of training. New recruits may be subjected to mind scans by other Green Lanterns or the Guardians of the Universe. They are taught to build mental defenses to protect themselves from psionic attack. The power ring can also be used to beam information from the ring wielder to another being. Green Lanterns have used this technique to share information regarding their enemies during combat situations.
Pocket Dimension: Within the ring exists the possibility of an entire world. When Green Lantern Abin Sur of Ungara defeated the evil sorcerer Myrwhydden, he reduced the magician to submicroscopic size and imprisoned him inside the power ring, into a world created by the Green Lantern's will. This undefined space may be a tesseract or a virtual reality created by the power ring. Whether or not this area exists in all rings has yet to be proven. Years after Abin Sur's death, Myrwhydden's power grew, allowing him to alter his environment and escape to battle the next Green Lantern, Hal Jordan. The power ring's interior appeared as a barren wasteland, dotted with dead trees and sea shells which Myrwhydden used during an escape attempt.
Security Protocol: The rings can be programmed. They are coded to the wearer to make them unusable if stolen. The ring will refuse to take an action that would kill a being unless they are on Oa or with permission. The Guardians recently removed the lethal force prohibition, first to allow lethal force against members of the Sinestro Corps, then against all enemies of the Green Lantern Corps.
Preset Conditions: Commands can be stored in the ring to be executed at a later date, even if the bearer is not wearing the ring.
Thought Relay: Otherwise known as a telepathic link.
Hope Symbiosis: When in the presence of a Blue Lantern Power Ring, a Green Lantern Power Ring gains a power boost, as well as allowing the Blue Lantern to fully utilize his or her powers.
Compassion Absorption: Similar to other lanterns natural "purge" of certain Power Rings, the Green Lanterns' Power Ring has the ability to absorb energy of Indigo Lantern's. This is made possible by their natural weakness found in Will Subversion.
Mental Instability Protocol: Drug use, neural interference, vertigo or other forms of mental incapacitation can render the wearer unable to use their ring.
Yellow Impurity: Formerly, the rings were unable to directly affect yellow. Now, a wearer can bypass this if they can 'accept fear', which is personified by the color yellow. Rookie lanterns are more susceptible to fear and thus vulnerable to the color yellow.
Rage Vulnerability: The Red light can corrupt the aura of a Green Lantern, draining the power of a Green Lantern Ring. Red Rage vulnerability has since been shown to be subject to the same restrictions as Yellow Impurity. While it will have a direct affect, its ability to entirely alter the user is dependent on the Green Lantern's ability to "understand", "accept", and "control" their rage.
Recharge Protocol: Formerly, the rings needed to be charged after a period of one planetary axial rotation (dependent on each ring's location), regardless of how often it was used. Currently, the rings retain a charge until they run out of power. This variability ensures that the wearer takes great effort to keep it charged.
Vibrational Interference: If a vibration from a device is set to a certain speed, it causes the ring to function only in miniature, so that if the user wanted to make hands to grab something, the hands would be smaller than intended. A clock has been seen to do this.