Stainless Steel Grease Fittings withstand severe and corrosive environments and offer greater corrosion resistance than traditional carbon steel grease fittings. SAE Products Stainless Steel Grease Fittings are comprised of Type 303 stainless for fitting bodies, Type 440 stainless for balls and Type 302 stainless for tempered springs. Stainless Steel Grease Fittings are also referred to as Stainless Steel Zerk Fittings, Stainless Steel Grease Zerks, and Stainless Steel Lubrication Fittings.