SportDog SDR-AC Add A Dog Collar - SDR-AC The original Collar Receiver for WetlandHunter 425CAMO. Add another dog to your current SportDOG Brand electronic training collar system or replace a Collar Receiver with the SDR-AC Add-A-Dog Receiver Collar. Comes with a convenient docking station that charges the collar in 2 hours. See description below for SportDOG systems that collar is compatible with.