Online Parts Store › Phillips Machine Screw - Flat Head, 5/16"-18 x 2-1/2" Image 1 of 1 Phillips Machine Screw - Flat Head, 5/16"-18 x 2-1/2" $16.00 18-8 Stainless Steel. Add To Cart Added! 18-8 Stainless Steel. You Might Also Like Phillips Tapping Screw - Truss Head #8 x 1/2" $18.52 Phillips Tapping Screw - Truss Head #10 x 1" $33.32 Square Tapping Screw - Flat Head,#12 x 2" $49.38 Square Tapping Screw - Flat Head,#10 x 1-1/2" $62.54 Phillips Tapping Screw - Pan Head, #10 x 1-3/4" $26.26