0.530" center hole diameter included on material diameter are two protrusions 180 degrees apart, being 0.005 wide by 0.003 high; nitrile (buna n) ; used on XM1
Used on tank,combat full trk; model m1,nsn 2350-01-061-2445; improve tank,modelm11a,nsn 2350-01-136-8738; armed battle tank,model m1e1,nsn 2350-01-087-1095.
0.281" hole diameter is reletive to shape of item being an oblique triangle with a bearing surface of 0.880 in. expanded in five places around its perimeter with a radius of 0.500 in around each bolt hole triangle
