1.9375" overall width 55.00mm bore diameter heat stabilized mil-m-17060 paragraph 3.6.1.9.6 also electric motor quality non-loading groove, non-separable cartridge type
sphericity to be within 0.001 in., thru colored, any except white or cream, min fail load of one ball to be 500 lbs, min average fail load to be 650 lbs tested between steel plates in a universal testing machine ball