Tracer silencer with inner left-hand thread 14 mm from Golden Eagle. The innovative silencer design reduces unwanted issuance visible flashes of the muzzle. Silencer can be turned on/off by pressing a button. As source serves 4 pcs AAA batteries (included). Description of function - when passing balls (special tracer type) silencers inside will discharge light that lit up the projectile during flight leaves a light trail.