Online Parts Store › Phillips Machine Screw - Flat Head, 5/16"-18 x 3" Image 1 of 1 Phillips Machine Screw - Flat Head, 5/16"-18 x 3" $18.14 18-8 Stainless Steel. Add To Cart Added! 18-8 Stainless Steel. You Might Also Like Stainless Countersunk Finishing Washer, #1/4 $21.92 Phillips Tapping Screws - Oval Head, #10 x 5/8" $28.59 Stainless Fender Washer 1/4", .062" Thick1/4", OD1-1/4" $59.33 Phillips Tapping Screw - Truss Head #8 x 1-1/4" $39.30 Phillips Tapping Screw - Pan Head, #8 x 3/4" $19.21