Clamp, 3" (75mm) capacity, Clamp Post 5-3/4" (145mm) long, .464" (11.8mm) diameter, fits swivel post snug 665D. Clamp is used to clamp the gage holding rod and the indicator into hard-to-reach places for inspecting jigs, fixtures, lining up work on centers and machine tables. Clamp has a 3" (75mm) capacity and a post with an approximate 5-3/4" (145mm) length. Clamp post is .464" (11.8mm) diameter that fits into the regular swivel post snug 665D.