Spring Calipers 6” (150mm) 3Pcs Divider, Internal & External Heavy Duty 3pcs Set- Inside, Out Side and Divider Size:6” 150mm These well-finished steel calipers and dividers have flat legs and strong springs. The fulcrum stud is hardened for durability. All sizes are available with either a solid or quick-spring nut. The quick-spring nut acts as a sliding speed nut, permitting quick adjustment of the legs. It engages only when it comes up against the leg post. The strong spring holds any setting accurately. Sizes indicated are maximum opening.