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 Phillips Tapping Screws - Oval Head, #10 x 3/4" $23.24 Phillips Tapping Screws - Flat Head, #6 x 3/8" $9.01 Stainless Cotter Pin 1/8" x 1" $63.67 Phillips Tapping Screws - Oval Head, #10 x 1-1/4" $28.85 Flat Washer, 5/16", .062" Thick, OD 7/8" $52.44