Online Parts Store › Phillips Machine Screw - Flat Head, 5/16"-18 x 1-1/4" Image 1 of 1 Phillips Machine Screw - Flat Head, 5/16"-18 x 1-1/4" $28.28 18-8 Stainless Steel. Add To Cart Added! 18-8 Stainless Steel. You Might Also Like Flat Washer, 3/8", .062" Thick, OD 5/8" (A/N Style) $11.46 Phillips Tapping Screw - Pan Head, #10 x 2-1/2" $37.66 Nylon Flat Washer 1/4", 0.56" Thick, OD 11/16" $24.88 Lag Screw, 3/8 x 3" $41.46 Phillips Tapping Screw - Pan Head, #12 x 1-1/4" $23.49