target practice in various environments, and train in realistic force-on-force scenarios. Performance Airsoft guns shoot plastic pellets at velocities from for a low-end spring pistol, to for heavily upgraded customized sniper rifles. Most non-upgraded AEGs are in the middle, producing velocities from to . The internal components of most guns can be upgraded which can increase the pellet velocity significantly. Using heavier pellets (.25 g, .3 g, etc.) will significantly reduce the gun's muzzle velocity, but can increase accuracy at range and reduce susceptibility to wind drift. Lighter pellets have less kinetic energy than their heavier pellets, despite their higher exit velocity. Decreasing the pellet's weight does not generally increase its range. A common upgrade done by players is in the "hop-up" system, featured in most mid- to high-end AEG's, as well as gas guns and spring sniper rifles. In this system, the wall of a rubber tube, called a bucking, is forced into the upper path of the pellet right before it begins flying down the inner barrel. This contact imparts backspin, which in turn gives the pellet a Magnus lift to maintain a flatter trajectory for a longer period of time. This is adjusted by screws or gears that cause the bucking to only show a small or large presence in the barrel. Different degrees of firmness of the rubber are considered when a hop-up is being upgraded. Safety Airsoft is safe when played with proper protective gear. Most airsoft guns on the market are usually below , but projectiles expelled from any type of airsoft gun can travel as slow as to more than and are capable of breaking skin at . For example, skirmish play in the United Kingdom has a maximum of 350 ft/s, with some airsoft locations having a limit as low as 290 ft/s. If under , the hit would have to be within a short range. Blood can be drawn, but injuries that do occur are predominantly superficial. Full-seal protective eyewear (goggles or glasses) is widely considered the minimum protection for airsoft players, as the eyes may be injured by any type of impact. The least amount of protection a player should seek will meet or exceed ANSI/ISEA Z87.1 standards, which indicates the eyewear is rated for ballistic strikes. Mesh eyewear has also seen some limited use by players due to low cost and its inability to fog, although it has drawn