EXTSW 3/8” ID x ( 7/8” / .865") OD x 3/16” Thick 316  Stainless Washer
Actual size .383" ID x .865” OD x .188" 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.