These handy double squares are indispensable for setting up machinery and for performing a host of shop layout tasks. They are manufactured in accordance with EEC Class 1 accuracy standards and are guaranteed to be square to within 0.002 (two thousandths of an inch) over the length of each blade. They have hardened and tempered no-glare satin chrome stainless steel blades. Blade marking are precision photo etched and then black filled for easy readability. Blades have Quick-Reading 4R markings (1/64ths and 1/32nds on one side and 1/8ths and 1/16ths on the reverse. Square heads are cast and then precision machined. Square head color is cobalt blue. Square heads lock down tight via locking knob. Squares come in a cardboard box. Available in with either a 4 or 6 blade. Spare blades and locking screws are also available. Specifications: Blade width: 0.728 inch +/- 0.01 inch Blade thickness: 0.078 inch +/- 0.008 inch Blade groove: 0.86 inch wide and 0.03 inch deep Graduations: Quick reading 4R (1/8, 1/16, 1/32, 1/64) Head thickness: 0.472 inch +/- 0.02 inch Head width: 0.084 inch +/- 0.02 inch Head height: 2.36 inch +/- 0.02 inch These handy double squares are indispensable for setting up machinery and for performing a host of shop layout tasks. They are manufactured in accordance with EEC Class 1 accuracy standards and are guaranteed to be square to within 0.002 (two thousandths of an inch) over the length of each blade. They have hardened and tempered no-glare satin chrome stainless steel blades. Blade marking are precision photo etched and then black filled for easy readability. Blades have quick Reading 4R markings (1/64ths and 1/32nds on one side and 1/8ths and 1/16ths on the reverse. Square heads are cast and then precision machined. Square head color is cobalt blue. Square heads lock down tight via locking knob. Squares come in a cardboard box.