Two replacement cylinder locks for the entrance door, 4 keys Used for entrance doors of apartments and multi-unit dwellings. Since they are two identical keys, you can lock and unlock the upper and lower locks with one key. Four keys are included. Ideal for replacing cylinders when moving in a rental property. The box is not included. Brand: MIWALOCK It doesn't mean you can't use it unless it's a two-door, two-lock system. The keys and the lock body seem to be the same specifications, so I think it's possible to install them on another door without sticking to the two-lock system. Of course, you can use only one and keep the rest as spare parts. I have added a little supplement. * Due to the nature of keys, we will only conduct transactions with anonymous shipping, and we cannot accept returns or refunds. Please consider carefully before purchasing. The product will be shipped in the box of another replaced product as "PC parts" via Yu-Packet Plus. * Since it is a used item, there are some signs of use, dirt, and scratches. Please refrain from purchasing if you are nervous, and only purchase if you understand. * We do not accept exchanges or returns due to different models or sizes. We will also accommodate bulk purchases. Thank you for viewing.