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 Phillips Tapping Screws - Oval Head, #10 x 2-1/2" $29.85 Seachoice 01011 Lock Washer ,5/16" $31.68 Seachoice 01008 Lock Washer, #12 $16.44 Stainless Fender Washer 1/4", .062" Thick, OD 1-1/2 $103.98 Stainless Cotter Pin 1/8" x 1-1/4" $65.75