A slide check is a valve used in pressurized

Pressure

Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 systems that lets air out ahead of it (the destination) while keeping pressure intact from behind it (the source). Slide checks are commonly used in paintball

Paintball

Paintball is a sport in which players compete, in teams or individually, to eliminate opponents by tagging them with capsules containing water soluble dye and gelatin shell outside propelled from a device called a paintball marker . Paintballs have a non-toxic, biodegradable, water soluble...

, mostly in remote

Remote

Remote may refer to:* Remote control, commonly known as a remote* Remote broadcast, commonly known in broadcasting as a person or a live remote* Remote access* Remote desktop...

 propulsion setups, to cut air off from the gun

Gun

A gun is a muzzle or breech-loaded projectile-firing weapon. There are various definitions depending on the nation and branch of service. A "gun" may be distinguished from other firearms in being a crew-served weapon such as a howitzer or mortar, as opposed to a small arm like a rifle or pistol,...

while keeping the remote pressurized. Slide checks are also useful when working with high pressure systems, such as hydro testing or audible air or leaks as you can rapidly apply pressure and release it without the frighting "pow" or projection of hoses with QD male {quick disconnect} fittings causing a dangerous hose whip motion.