SportDOG Brand FieldTrainer 425S Add-A-Dog Collar - Additional, Replacement, or Extra Collar for Your Stubborn Dog Remote Trainer - Waterproof and Rechargeable with Tone, Vibration, and Shock This is the SDR-AS Collar Receiver on a 3/4" Red Collar Strap only; compatible with the SportDOG Brand FieldTrainer 425S (SD-425S) The FieldTrainer 425S Stubborn Dog Remote Trainer can be expanded to train up to 3 dogs with the same Remote Transmitter with the purchase of this SDR-AS Add-A-Dog Collar Features DryTek technology making this collar waterproof and submersible to 25 feet; fits dogs 8 pounds or larger with neck sizes 5"-22" Rechargeable lithium-ion batteries charge in 2 hours and last 40-60 hours per charge; features a low battery indicator to let you know when to charge Detailed operating guide and a locally based Customer Care Center, reachable at 844-209-4636, provide support when you need it