Curv-O-Mark® Centering Heads aid in the setting of centre lines, establishing angles and marks for buttins, locating points inside pipes and tanks, laying out keyways and measuring declivity. The Jumbo Centering Head is for pipe 1-in. diameter and up. It has an 8-in. Y-type head, and a DSL. A spring loaded hardened centering pin eliminates the need for a hammer. Just make the alignment and press the trigger.