Mindy 50mm padlock is a high precision key, no key copying. It is the best advantage of burglar-proof locks. It is built by 30 piece steel sheets. When opening it is through key steps length to separate steel sheets and aiming at shaft slots. Only when the three steel sheets are aiming at the three slots at the same time will it rotate and open. If the key steps are different, it is not feasible to rotate and open even if the slots dimension errors is within 0.1mm. The key hole are in circle shape it will be in vain to try to open by any special instruments. Owing to its unique structure. It play an important role of “keep away” for the skeleton keys and ultrasonic vibration key.