Used to measure the distance between points that are too great to be reached with dividers|The heads are die cast and have hardened, forged steel divider points|The points screw into the heads, and the pencil socket accompanying each set of trammel heads can be used in place of either point|Die cast heads with black wrinkle finish|Heads accommodate a beam (not supplied) up to 3/8 in thick and 3/4 in wide