Tightening Screw Boxed Set Screw Assortment. Standard metric and imperial sizes are in ready stock for fast delivery, with customized non-standard length, thread pitch, surface treatment and packaging available forCustom Boxed Fasteners. Precisely made of high-strength carbon steel and stainless steel, these headless set screws feature accurate threads, high hardness and strong tightening force for reliable anti-loosening and positioning. Classified box packaging simplifies inventory management and equipment maintenance. As essential industrial Boxed Fasteners, they are widely used for locking and positioning mechanical shafts, molds and transmission parts.