Conceived by timber framer Steve Chappell, these squares have all the standard features of traditional models, but are graduated in 20ths of an inch (0.05"), allowing you to transfer figures from a calculator without complex conversion, minimizing rounding errors. All markings are deeply etched and black filled for legibility and wear resistance, and are sharply defined to permit precise interpolation between marks; in practice, this gives most users the ability to easily mark and measure to within 0.025". Longer marks at 5/20", 10/20" and 15/20" give you a quick visual reference to standard 1/4", 1/2" and 3/4" increments.
Another helpful reference is that all scales are marked at 16.97", the standard unit run of a hip/valley rafter. The squares include the usual hip, valley and jack rafter tables, but also incorporate newly developed tables for unequal, hexagonal and octagonal roofs. The small square has an 18" blade and a 12" tongue; the large has a 24" blade and an 18" tongue.
Made of sturdy, rust-resistant 13-gauge 304 stainless steel, both squares are machined on all edges. Relieved inside corners ensure that the squares seat well, even over saw whiskers. Graduations and angular accuracy are to within ±0.003" over the length of both tongue and blade. Well made in USA, this is a versatile and clever design.