EXTSW 1/2” ID x 3/4” OD x 1/8” Thick 304 Alloy Stainless Washers
Actual size .506" ID x .740” OD x .125" thick 
(+/- .003" on all dimensions) 
.030 inch Radius OD / slightly countersunk ID (no sharp edges)
 Made in USA. 304 Stainless has very GOOD corrosion resistance.