Inner Barrel Insert (212.55mm) for Airsoft Grenade Launcher -190 - Complements APS 870 Shotgun Shells - Airsoft3DThis Inner Barrel Insert works with the Airsoft3D Aliens M40 HEDP Grenade Shell and the APS 870 Shotshell to provide a more precise barrel for the Grenade Launcher. This Inner Barrel Insert has been tested to be compatible with the following products: Required: Airsoft3D Aliens M40 HEDP Grenade Shell (130mm) for APS 870 Shotshell APS 870 CO2 Airsoft Shotshell ICS MGL Airsoft Grenade Launcher ICS 190 Optional: Airsoft3D A310 Muzzle for Grenade Launcher