The Flash suit is protective armor-plated suit designed and created by the Founder and Director of S.T.A.R. Labs, Harrison Wells. It is used by Barry Allen for his superhero and vigilante activities as The Flash.
Aerodynamics: The suit's form-fitting design and articulation allows Barry to maintain control of every step and movement that he takes. This is what allows him to dodge attacks and run as he would without it.
Communications link: Dr. Wells had installed two winged lightning-bolt shaped miniature earpieces attached to the ears of the suit. This grants Barry full communication with the team at S.T.A.R. Labs while in the field. The link can be routed to other people's phone and display it as if it was from his cell phone.
Defibrillator: A newer addition to the suit is a magnetic-electrical charge that jumpstarts Barry's heart. Though after two consecutive administrations, the device will completely fried and take a while to repair, making it still a prototype.
Dwarf Star alloy chest armor: After getting some of this material from Ray Palmer, Dr. Wells was able to fit the suit with this highly durable material, protecting the wearer from extreme blunt-force trauma to said area. However, enough force, such as from a meta-human with superhuman strength, can potentially destroy the armor even if the strike itself is blocked, leaving the wearer vulnerable again to any further blows until the armor itself is repaired.
Identity concealment: Barry uses a red helmet to conceal his identity and to keep his friends and family safe from harm.
Force Resistance: It's made of specific fibers, reinforced tripolymer, it is also made from the same material that NASA uses to protect spaceships from burning up as they re-enter Earth's atmosphere making it resistant to several thousand degrees of intense heat, whether it be around Barry or it be the friction generated from his body while running; as well as resistant from grazing bullets, knives, abrasions, or scars. It appears that Dr. Wells has modified it to resist intense cold as well, since Barry was able to walk off several blasts from Leonard Snart's Cold Gun and Mick Rory's Heat Gun quicker than in previous battles.
Mini-camera: The suit's chest piece has a miniature camera with live streaming and 2160p built into it. By pressing on it, Barry's team can see through and gain a better idea of his surroundings or situation.
Performance enhancement: The newest addition to the suit, the tachyon unit, was able to fit inside the lighting bolt emblem to conceal the device from Zoom. Because of this, while wearing the suit, it will allow a speedster's vitals to remain at peak performances, including keeping their calorie burning rate at a normal level, and thereby able to continue moving at top speeds for much longer durations unhindered from effects such as dizziness a fatigue. It was destroyed after Barry was absorbed into the speed force and his suit was destroyed.
Sensor system: Barry's suit has several health sensors built in to work in real time. The telemetry is sent to S.T.A.R. Labs so that they can identify Barry's condition and health. The suit has a GPS built into it so that S.T.A.R. Labs can keep track of where he is, see how much power he's generating, and determine how fast he's running.
Therma-threading: One of the latest modifications to the suit, Dr. Wells has added "therma-threading" to the suit, which causes the suit to generate a large amount of heat, in case Barry gets hit by the Cold Gun, which is why it was designed.
Voice alterer: Due to losing his speed to Zoom, the suit also apparently has a voice filter equipped to disguise Barry's voice, since he couldn't do it himself. It is unknown what happened to it after Jay got his powers back, it is presumed it was either removed or kept in the suit in case Barry loses his powers again.