Extend-A-Chime, Wireless, Battery Operated, Use With Existing Wired Door Chime To Hear In Remote Areas Of Home Or Yard, Weatherproof For Indoor Or Outdoor Use, 2-1/4" Speaker For Great Sound Quality, Receiver 1.63"L x 3.75"W x 6.75"H, Can Be Mounted Vertically Or Horizontally, Safe & Easy To Install, 150' Operating Range, Uses 4 "C" Cell Alkaline Batteries, Not Included, Clam Shell Pack.Thomas & Betts