The bench grinder safety gauge is laser-cut, Grade 5052 aluminum with H32 hardness with an 18" 18/8 stainless steel tether. The safety yellow, durable powder-coated gauge has silk-screened text and graphics. It measures 2 3/4" wide by 2 1/4" high by .1000" thick and has a 1/4" hole for attachment to the bench grinder. OSHA 29 CFR 1910.215 specifies that work rests must be kept adjusted closely to the wheel with a maximum opening of 1/8" to prevent the workpiece from being jammed between the wheel and the rest. OSHA also states that the distance between the grinding wheel and the adjustable tongue must never exceed 1/4".