B-Square handgun bases lock to the firearm using the ventilated rib or existing predrilled holes in the firearm and require no gunsmithing. Rib mounts are full length for maximum eye relief adjustment. Require Weaver-Style rings (not included). Material: Aluminum. Style: Weaver. Fits: Taurus Models 44 Magnum Model 607 608 and 689. Notes: Fits vent rib guns with non-ported barrels from 6'' up to 8 3/8'' in length. See-thru capability allows use of iron sights. Mounting Hardware Included.UPC: 54082423066