The 12" Combination Set with Square, Center and Non-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, and hardened steel, photo-engraved blade. Cast iron heads with black wrinkle finish. FEATURES: Reversible lock bolts, scriber, spirit level in both square head and protractor head. Direct reading double 180 Deg protractor scale. Direct reading double 180 Deg protractor scale. Non-reversable protractor head. Hardened steel, machine divided blade. Satin Chrome Finish Blade. Cast Iron Heads with Black Wrinkle Finish.