This is a wonderful loud extension bell and has a proper mechanical 700 series double bell inside. It will give the correct sound of a Bakelite GPO 300 Series telephone and would be ideal to go with a 200 series to add the proper GPO bell sound. This can be simply plugged into any telephone socket in the house and would be ideal to add extra bells to the hard of hearing or in a noisy workshop etc. It comes with full fitting instructions and screws and to connect it simply plug in and go.
Dimensions are 14cm X 14cm X 4cm.