In airsoft silencers are usualy used to give the gun a cool look and don't improve the guns performance however they can be used to cover up and extended tightbore barrel (the tightbore barrel increases accuracy and slightly increases fps) they can also reduce the sound of a gun. Tracers units are usualy put into silencers and when used with special tracer bbs they can glow in the dark when shot which gives a very cool effect. Charie has both a tracer and a silencer Click here for the silencer unboxing