The Starrett C33H Combination Square is a 6 in combination square with a forged, hardened steel square head and a satin chrome blade, for layout and for checking square and 45 degree angles.
The head is forged and hardened steel with a smooth black enamel finish, and it has a spirit level, a scriber and a reversible lock bolt. The hardened steel blade is machine divided with Starrett's 4R graduations: 8ths, 16ths, and quick-reading 32nds and 64ths.
Laroy S. Starrett, a Maine farmer's son, patented the combination square in 1879 and founded the L.S. Starrett Company in Athol, Massachusetts, in 1880. Its headquarters and largest plant are still in Athol.