Description: Arc Rail Adapter for Comtac Communication Headset(Black) Z-Tactical Helmet Rail Adapter Set for Comtac I/II Headset. Compatible with Element / Z-Tactical Comtac I & II style headset. Works with the ACH-ARC Kit and the FAST Helmet rails. Quickly attaches or releases from the rail. Fit OPS-Core helmet rail. NOTE: Helmet rail or headset is not included in this item.