This outer barrel is compatible with the M4 series

Machined aluminum topside mount and underside mounting base

The M/S or FPS can vary considerably due to your entire build setup

you can choose the installed spring

polyester reinforced layer

SS Airsoft Custom AEG Centaur AK - Destroyer 11.1v Li-Ion Battery This outer barrel is compatibleSS AIRSOFT Custom Built AEG airsoft rifle. We build some of the best custom AEG airsoft replicas you will find on the market. All weapons are test fired, tuned and adjusted to work perfectly right out of the box. Some products may or may not have orange tips. Please call to verify if necessary. Parts List Arcturus CT02 Centaur AK Airsoft Rifle Lancer Tactical 4x32 Magnified Scope w Micro Red Dot AN PEQ 15 L. E. D. White Light + Laser (Green Laser)