Online Parts Store › Phillips Machine Screw - Flat Head, 5/16"-18 x 1-1/2" Image 1 of 1 Phillips Machine Screw - Flat Head, 5/16"-18 x 1-1/2" $30.99 18-8 Stainless Steel. Add To Cart Added! 18-8 Stainless Steel. You Might Also Like Phillips Tapping Screw - Pan Head, #10 x 2-1/2" $37.66 Stainless External Tooth Lock Washer 3/8" $34.20 Phillips Tapping Screws - Flat Head, #12 x 2-1/2" $41.63 Square Tapping Screw - Oval Head #10 x 1-1/2" $35.29 Phillips Tapping Screw - Truss Head #8 x 1" $30.99