The 12" Combination Set with Square, Center and Reversible Protractor Head and Blade includes a reversible lock bolt, scriber, spirit level in both square head and protractor head, direct reading double 180° protractor scale, hardened steel, photoengraved blade. The square heads and center heads are forged, hardened steel with smooth, black enamel finish. FEATURES: Reversible lock bolts, scriber, spirit level in both square head and protractor head. Direct reading double 180 Deg protractor scale. Hardened steel, machine divided blade. Satin Chrome Finish Blade. Forged and Hardened Steel Heads with Smooth Black Enamel Finish.