TS TAC-SKY 2.0 ARC Rail Helmet Mounting C2 Tactical Headset Electronic Pickup Hearing Protection Silicone Earmuffs + PTTDescription 1. The bracket rail adapter is the center rail of the ARC OPS helmet, which is suitable for most FAST series helmets, ACH series helmets and MICH helmets. 360 free rotation, the rail bracket can be fixed on the helmet sides of the helmet rail, the center telescopic rod can be adjusted freely. 2. The ear cups are made of silicone, which is more comfortable to wear and can bring better wearing experience compared with sponge ear cups. 3.