Wireless doorbells are now very popular as they are easy to install and relatively inexpensive. Most come with either a plug in chime or a portable battery operated chime. The bell push is battery operated and comes in various shapes and sizes and will send a signal to a portable device that you can carry in your pocket if you happen to be working at the bottom of the garden. Signal ranges are from around 50m to 150m depending on the portable bell kit you buy.