1/2“ ID x 1 1/4” OD x .343“ Thick 316 Stainless Washer
Actual size .507" ID x 1.240" OD x .343" Thick
(+/- .003" on all dimensions) 
.030 inch Radius OD / slightly countersunk ID (no sharp edges)
Made in USA. 316 Stainless has the ULTIMATE corrosion resistance.