Keson wood rulers have long been an essential tool for carpenters, mason’s, 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. Designed for engineer or other measurements requiring tenths and feet. Decimal points on engineer’s scale prevent reading errors. Units: ft, in, 1/8, 1/16 & ft, 10th, 100ths.