Suppressor

A Suppressor (or "Silencer") is a generally cylindrical component that is designed to muffle/dampen the firing sound of a weapon.

Suppressors act by using a series of insulated baffles through which the projectile passes leaving behind the escaping gases to disperse around the inner materials overall quietening the final sound.

In Air Guns
In Air or CO^2 powered weapons the suppressors tend to increase accuracy and silence the shot. Though not regarded as useful for spring-powered airguns, home-made pre-charged pnuematic weapons produce loud gasps and so the attachment of homemade suppressors helps to insulate the noise allowing only the BB to escape.