This wireless doorbell is an ideal solution for people who are hard of hearing and who struggle to hear when visitors are at the door. The doorbell unit is secured to the door using the adhesive strip provided and the chime unit can be placed within the house wherever the user will hear it best. With a range of up to 100 Metres it is ideal for people who are gardening and dont want to miss a visitor, delivery etc. This wireless doorbell has 36 Melodies to choose from which can be changed simply with the touch of a button. Easy installation makes it an almost instant solution. Requires 2xAA batteries (not included). Approx. 115dB. mysmartbuy Battery Powered Wireless Doorbell & Receiver with 100m Range, LED Flash & 36 Melodies - White & Blue Cordless Loud Door Chime