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 Stainless Cotter Pin 1/16" x 3/4" $17.76 Stainless Cotter Pin 5/32" x 2" $84.08 Nylon Insert Locknut - Stainless 10-32 $25.51 Flat Washer, 3/8", .062" Thick, OD 1" $38.36 Phillips Tapping Screws - Oval Head, #10 x 5/8" $28.59