SeaKing Stores › M8 x 50mm A4 stainless socket-cap bolt - EACH M8 x 50mm A4 stainless socket-cap bolt - EACH £0.40 M8 thread diameter x 50mm length. A4 stainless steel socket-cap screw. Sold individually; quantity 10 means ten loose bolts. Add To Cart Added! M8 thread diameter x 50mm length. A4 stainless steel socket-cap screw. Sold individually; quantity 10 means ten loose bolts.