M5 Thin type nylon insert lock nut. A4 grade stainless steel Nyloc Type d = 8.79 mm h = 5 mm m = 3.2 mm s = 8 mm thread pitch = 0.8 mm Nylon insert can be various colours. Please ask if colour is important to you A4 grade stainless steel has a greater corrosion resistance than A2 in certain environments. It is often used for Marine applications especially when coming into direct contact with salt water DIN985