Flexible and Rigid Made from the finest quality stainless steel available All rules fully hardened and tempered Satin chrome finish Precisely etched, then black filled for readability Graduations: 3R (32nds, 64ths, 10ths, 50th) 4R (8ths, 16ths, 32nds, 64ths) 5R (32nds, 64ths, 10tmore...