Online Parts Store › Phillips Machine Screw - Flat Head, 1/4"-20 x 3-1/2" Image 1 of 1 Phillips Machine Screw - Flat Head, 1/4"-20 x 3-1/2" $41.13 18-8 Stainless Steel. Add To Cart Added! 18-8 Stainless Steel. You Might Also Like Phillips Tapping Screws - Flat Head, #8 x 1/2" $12.41 Phillips Tapping Screw - Pan Head, #8 x 5/8" $18.01 Phillips Tapping Screws - Flat Head, #8 x 3/8" $11.90 Flat Washer, 5/16", .062" Thick, OD 7/8" $21.67 Socket Set Screw 10-24 x 1/4" $22.63