Using standard half inch pipe as a trammel bar, heads feature radius set points cast in alignment with marking pointers for easy setting ,Equipped with 1/4” screws and squared on the back side of perpendicular alignment. ,The stationary head holds a 1/4” case hardened center point. Moveable head has a 1/8” steel scribe hardened. ,Marks from 1-1/2” circle to any diameter needed, depending on length of pipe used as a trammel bar ,Allen wrench, soapstone, scribe and pointer also included.