Keson wooden 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. Graduated in feet, 10ths and 100ths Regular outside marking in feet, inches, graduated to 1/16-inch Engineer’s side has foot marks in red, and decimal points