You've got mail mailbox signaling device

Abstract

The present invention provides a transmitting and receiving system that provides an audible alert, inside the home, that mail has been left in an outside box. The transmitter is an electronic unit featuring a frequency generator, amplifier, internal antenna, and the required electrical and electronic components and circuitry encased within a durable plastic housing. Also enclosed within the plastic housing, a battery source is used to power the unit. This transmitter is wired into the flag of the mailbox, and activated as soon as the flag is raised. Rectangular in shape and containing intricate components, the receiver, which is kept inside the home, consists of a tuned frequency, receiver circuit, replaceable silver oxide battery, such as the type common to wristwatches, and a speaker, all enclosed within a sturdy, plastic housing.

Dependencies are inferred from the claim text.