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 Square Tapping Screw - Flat Head,#10 x 1-1/2" $62.54 Phillips Tapping Screws - Flat Head, #6 x 3/4" $10.33 Lock Washer, M4 $10.20 Flat Washer, 5/8", .078" Thick, OD 1-1/2" $22.42 Seachoice 01533 Hex Nut, 1/2-13 $66.78