Combina tion Square Blades Square Heads, Center Heads and Protractor Heads for Combina tion Squares, Combina tion Sets and Bevel Protractors The heads listed fit any blade according to the sizes noted in the charts on all combination squares, combination sets and bevel protractors. Sizes 12", 18", 24", 36", and 48" and 300mm and 600mm are interchangeable. When ordering, specify complete catalog number and length of blade. Exception: Starrett 33J and 8 Combination Squares. (For these, see 33J and 8 listings.) H11-1224 C33-1224 PR-1224S Square Heads Only for Combination Squares, Combination Sets and Bevel Protractors Cast Iron Black Wrinkle Finish Forged and Hardened Steel with Smooth Black Enamel Finish Fits Blade Size Cat. No. EDP Cat. No. EDP H11-4 50069 H33-4 50223 4" H11-6 50070 H33-6 50224 6" H11-1224 50071 H33-1224 50225 12" (300mm) 18" 24" (600mm) Center Heads Only for Combination Squares, Combination Sets and Bevel Protractors Cast Iron Black Wrinkle Finish Forged and Hardened Steel with Smooth Black Enamel Finish Fits Blade Size Cat. No. EDP Cat. No. EDP C11-4 50072 C33-4 50226 4" C11-6 50073 C33-6 50227 6" C11-1224 50074 C33-1224 50228 12" (300mm) 18" 24" (600mm) Protractor Heads – Cast Iron (Fits blades 12" and up) for Combination Squares, Combination Sets and Bevel Protractors Reversible Nonreversible Finish Cat. No. EDP Cat. No. EDP PR-1224W 52525 PNR-1224W 50107 Black Wrinkle CPR-1224W 64601 CPNR-1224W 50108 Black Wrinkle, Chrome on Turret PR-1224S 52515 Black Smooth CPR-1224S 52516 Black Smooth, Chrome on Turret For prices of lock bolts, contact the Parts Department. 4" Center Head Max. Inspection Dia.: 3.125" 6" Center Head Max. Inspection Dia.: 4.3" 12"-24" Center Head Max. Inspection Dia.: 5.3" 273 starrett.com S quares