The 24" Combination Set with Square, Center and Reversible Protractor Head and Blade features reversible lock bolts, 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. Regular Finish Blade. Cast Iron Heads with Black Wrinkle Finish.