Burris, Smartclip, BTC Adapter, Fits 56mm, Quick Detach, Matte Finish, Black CA PROP 65 WARNING: This product may contain chemicals known to the state of CA to cause cancer, birth defects or other reproductive harm. Screw on Adaptor Fits Burris Thermal Clip On Quick Detach Lever 56mm Product Description Quickly mount the Burris Thermal Clip-On (BTC) to your favorite riflescope using our clip-on adapters. Options available are for 38-64mm objective lenses. Screw on the adapter to your Burris Thermal Clip-On and secure to your optic's objective lens using a quick-detach cam lever.