Martin Tools 632MM Check Nut Wrench, Industrial Black, 32MMMartin Tools 632MM Check Nut Wrench, Industrial Black, 32MM Metric Check Nut wrenches are drop forged from steel bar. These wrenches are available in fractional sizes from 1 2 through 1 11 16 and in Metric sizes from 10mm through 41mm. These industrial black wrenches are used on check nuts, stop nuts, jam nuts, and hydraulic fitting. The smaller sizes compliment service wrenches. (Also referred to as Thin Head Wrench) These are special purpose