Online Parts Store › Stainless Countersunk Finishing Washer, #4 Image 1 of 1 Stainless Countersunk Finishing Washer, #4 $13.29 316 Stainless Steel. Add To Cart Added! 316 Stainless Steel. You Might Also Like Flat Washer, #4, .032" Thick, OD 5/16" $6.74 Phillips Self Drilling Screw - Pan Head #10 x 3/4" $36.40 Phillips Tapping Screws - Flat Head, #6 x 1-1/2" $16.94 Phillips Tapping Screws - Flat Head, #14 x 3" $59.58 Square Tapping Screw - Oval Head #8 x 3/4" $25.25