BKL 3/8" or 11mm Dovetail to Weaver Cantilever Adapter, 4" Long, Matte Black 3/8" or 11mm dovetail to Weaver adapter (rail accepts Weaver mounts) 4" long 2 screws in base Ideal for dot sights Matte black BKL mounts have the unique ability to flex, giving them superior gripping power! Your mount may look like it's bending, but it's supposed to do that...it's grabbing and tightly holding your optics on your gun. BKL's patented Auto-Centering design overcomes problems caused by varying dovetail or rail widths.