Sconi AUTOCOCKER Freak Insert Barrel Back Compatible DYE - DUST Black Fits Autococker threaded guns Includes 2x O-rings inside to hold Freak Inserts Front threads are for Dye Ultralite barrel tips Aluminum Anodized Dust Black This barrel back is aprox. 1 shorter than a standard Dye barrel back so your overall barrel length will be shorter by 1.