With the revised key holder, the Nuki Smart Lock 2.0 is now compatible with common knob cylinders. The adapter serves as a connector between the knob cylinder and your Smart Lock 2.0. In the next step, select the manufacturer of your cylinder so that the appropriate adapter for your knob cylinder can be added. You can often find the manufacturer of the cylinder (e.g., EVVA, CISA, KESO, etc.) on the outside of your door. The illustrated matrix provides an overview of the shape your adapter can take. 6x8 mm.