771-Wired-Wall-Mounted-Doorbell-Byron-771-p-The-Byron-771-Wired-Doorbell-is-suitable-for-wall-mounting-&-makes-the-classic-lsquo-ding-dong-rsquo-sound-The-chime-can-be-powered-by-batteries-or-mains-electricity-with-a-8V-transformer-It-can-be-connected-to-your-current-bell-push-If-you-want-to-mount-the-door-chime-far-from-the-meter-box-&-do-not-want-to-install-extra-cables-you-can-power-it-by-using-a-9V-block-battery-not-included-You-can-use-the-door-chime-near-your-meter-box-and