Online Parts Store › Nylon Insert Locknut - Stainless 4-40 Image 1 of 1 Nylon Insert Locknut - Stainless 4-40 $21.16 18-8 Stainless Steel. Add To Cart Added! 18-8 Stainless Steel. You Might Also Like Stainless Countersunk Finishing Washer, #6 $13.10 Stainless Fender Washer #8, .050" Thick, OD 3/4" $21.67 Nylon Insert Locknut - Stainless 5/8-11 $35.08 Nylon Insert Locknut - Stainless 1/2-13 $35.14 Phillips Tapping Screw - Truss Head #10 x 1-1/4" $50.76