SportDOG WetlandHunter 1825X Add-A-Dog Collar - The Collar Receiver for WetlandHunter 1825X Remote Trainer. Add another dog to your current SportDOG Brand electronic training collar system or replace a Collar Receiver with the SDR-AXW Add-A-Dog Receiver Collar. For dogs 8 pounds or larger with neck sizes 5in - 22in Charges in 2 hours, lasts 140-160 hours per charge