The 24" 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, photo-engraved blade. 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.