The function of Pairlock is just the same as the common padlock's on the market; besides, it has the whole new product appearance and structure, along with the lock core, the password of which can be changed. It is a pioneering work of lock design. Users can change the password on lock core, and the key’s password corresponds to the change. Users are able to use only one key to manage a great amount of padlocks. It will be more secure since they can change the password at any time.