The Nuki Smart Lock 3.0 makes your smartphone the smart key. The electronic door lock is mounted on the inside of your door over the existing lock cylinder within a few minutes and is not visible from the outside. With the free app (iOS/Android) you open and close your door without any key. You can also create up to 200 permanent, temporary, or recurring virtual keys using the Nuki app. With it your family and friends, dog sitters and cleaning staff have access exactly when you want. The most modern encryption mechanisms achieve the highest possible security standard. You can remove your Nuki Smart Lock without leaving any residue, so it is ideal for rental properties.