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 Lock Washer, M4 $10.20 Phillips Wood Screw - Flat Head, #10 x 1-1/2" $44.84 Nylon Insert Locknut - Stainless 3/8-16 $28.40 Phillips Tapping Screws - Oval Head, #12 x 1" $45.16 Square Tapping Screw - Flat Head,#8 x 1-1/4" $28.68