M4 Countersunk Socket Screws. M4 countersunk socket screws. A2 Stainless Steel Hexagon. M4,M5,M6,M8 A2 Stainless Steel. Hexagon Head Fully Threaded. M4, M5, M6, M8mm. A2 Stainless Stee l. Manufactured from A2 grade stainless steel for improved corrosion resistance.