Dogtra Bird Launchers allow excellent air flow for scent distribution. Spring tension allows adjustment of throwing height. The remote release system has the same quality digital electronics found on the Dogtra training collars. The transmitter and receiver feature NI-MH rechargeable batteries. Launchers come with a locating horn and duck sound on the receiver to help you locate your launcher in the field. One transmitter will operate up to 8 receivers with a 1 mile range.