Mail Chime alerts you the instant your mail is delivered -- no wondering, worrying or guessing! Now you'll never trudge out to the mailbox in bad weather only to come back empty handed. And you won't have to worry about your mail getting stolen before you get to it. This revolutionary system sends a signal from a sensor in your mailbox to an indoor receiver up to 450' away that alerts you with a bright red LED and four audible beeps. Works with most standard mailboxes (except those with vertical hinges). 12V battery included. Receiver works on AC power. 1-year limited warranty.