The Byron DBY-23524UK Twin-Pack is the perfect easy to install doorbell for any home no need for wiring. Just follow the simple step by step instructions and your new doorbell will be working in no time. This Doorbell comes with a both a portable and a plug in chime unit which can be plugged in to any standard UK plug socket giving you the flexibility to move your door chimes anywhere throughout your home garden or garage. The portable unit requires 3 x AA batteries (not included) and both units will ring up to 200 metres (open distance) from the bell push.