M4 x 55mm Socket Cap Head Screws (DIN 912) - A4-80 Stainless Steel Socket Cap Head Screws are a widely used machine screw, featuring an internal socket drive, and are fastened with a Hexagonal\/Allen key. Due to this they are very versatile and easily accessible as the internal drive allows for a smaller head diameter than seen on other machine screws. These Socket Cap Heads are made from A4 Marine Grade Stainless Steel which provides corrosion and oxidation resistance as well as increased resistance in harsh chemical and outdoor environments. For larger quantities or custom sizes, please email and one of our team will provide you with a quotation. M4 x 55mm Socket Cap Head Screws (DIN 912) - A4-80 Stainless Steel