Slim rearsight tube that acts as a mount to attach the Centra Duplex to a variety of rearsights Screws into the front of the rearsight, and threading at the other end allows the fitting of the Centra Spy filters There are several versions available: Anschutz Old Type fits the OLD Anschutz steel rearsights (not 6805), MEC Free Sight, Centra 10/50, Gehmann 590/595/598 Anschutz 7002 fits the 7002 reasight & Centra Pro57 The others are self-explanatory *NOTE* The photo shows one version, the tube length & threading will vary to be compatible with your sight selection
