Keson wood rulers have long been an essential tool for carpenters, masons, plumbers and all types of tradespeople. They extend to over 6 feet (2M). they enable you to draw straight lines up to these lengths without the use of a chalk line or mason’s line. The brass extender makes measuring tight openings a snap. Extends up to 6 inches, and sliding Rule stops at each end to resist falling out. A very useful tool for carpenters. Units: ft, in & ft, in with 6 inch extender.