Starrett 9-12-4R 12-Inch Quick Read Combination Square Set with Cast Iron Head Cast iron heads with black wrinkle finish Graduation: No. 4R - 1/8", 1/16", quick reading 1/32", 1/64" 4R Grad: 8ths, 16ths, Quick Reading 32nds, 64ths Reversible lock bolts Hardened steel, machine divided blade Cast iron head