This pack of 100 Master Spool Driver Pins is designed to increase the security of Master Padlocks. They are constructed from Full-Hard #360 Alloy Brass, ensuring durability and reliability. With a length of .135 inches and a diameter of .093 inches, these spool pins are specifically designed for use with Master Padlocks. Theseare a substitute for OEM Part Number 6121-0419.Proudly made in the USA, these pins are an essential addition to any Master or Master style padlock cylinder.