M8 Thin type nylon insert lock nut. A4 grade stainless steel Nyloc Type d = 14.38 mm h = 8 mm m = 5.5 mm s = 13 mm thread pitch = 1.25 mm Nylon insert can be various colours. Please ask if colour is important to you A4 grade stainless steel is also known as type 316 S31.This has a greater corrosion resistance than A2 in certain environments, and is often used for Marine applications especially when coming into direct contact with salt water.. DIN985