Online Parts Store › Lag Screw, 5/16 x 4" Image 1 of 1 Lag Screw, 5/16 x 4" $161.93 Hot Dipped Galvanized. Add To Cart Added! Hot Dipped Galvanized. You Might Also Like Stainless Cotter Pin 1/16" x 1/2" $9.76 Phillips Tapping Screws - Flat Head, #6 x 1" $11.21 Stainless Countersunk Finishing Washer, #6 $13.10 Stainless Fender Washer 3/8", .078" Thick, OD 1-1/2" $54.73 Phillips Tapping Screw - Truss Head #8 x 1-1/2" $63.30