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 Seachoice 01008 Lock Washer, #12 $16.44 Phillips Tapping Screw - Pan Head, #12 x 2" $30.36 Phillips Tapping Screws - Flat Head, #6 x 5/8" $9.57 Nylon Insert Locknut - Stainless 5/16-18 $18.01 Phillips Tapping Screw - Truss Head #8 x 1/2" $18.52