Shackle padlock steel of size 30 millimeters by the company Lifeventure, it is for general use depending on your need, some places we encounter it include gate doors, garages, etc.. The locking and unlocking method is done by the combination of numbers on the lock. You don't need to carry keys but you definitely need to remember the combination. Comes with TSA certification, which essentially allows security authorities (e.g., airports) to unlock and inspect your luggage without damaging it.