The security combination lock has a cylinder length of 1 1/8\" (30 mm) and is suitable for material thicknesses up to 7/8\" (23 mm). The cylinder diameter is 3/4\". Please measure this to ensure you purchase the correct lock. This combination lock is keyless, resettable, and has 3 digits, making it secure with 1000 possible combinations. The default combination is 0-0-0. Easy to install: there is a hole behind the lock. Use a small pin to press the hole and then enter your new password simultaneously. Remember this password, release the pin, and your password is changed. The combination lock is made of zinc alloy and chrome-plated. The combination lock comes with a lock accessory and English instructions. Used for keyless applications on cabinets, doors, wardrobes, drawers, lockers, mailboxes, safes, office cabinet locks, and is ideal for protecting important and dangerous items.