Dogtra Remote Release Deluxe Extra ReceiverThe Dogtra Extra Receiver features two sound modes authentic mallard duck call attention getter or a beep locater sound. The receiver can operate two launchers with the use of a 15 foot jumper cord. The Dogtra extra receivers are water resistant and are programmable, so you can start with a smaller system and later add launchers without having them specially built to match your system. Features: Multiple Sound Modes Realistic Duck Call for Retriever