Online Parts Store › Cap Screw - Hex Head, 5/16"-18 x 3-1/2" Image 1 of 1 Cap Screw - Hex Head, 5/16"-18 x 3-1/2" $26.01 18-8 Stainless Steel. Add To Cart Added! 18-8 Stainless Steel. You Might Also Like Socket Set Screw 10-24 x 1/4" $22.63 Stainless Cotter Pin 5/32" x 1-1/2" $64.12 Stainless Cotter Pin 1/8" x 1-1/2" $55.55 Stainless Countersunk Finishing Washer, #8 $14.36 Nylon Insert Locknut - Stainless 1/2-13 $35.14