Add another dog to your current SportDOG Brand In-Ground Fence system (SDF-100A) or replace a Collar Receiver with the SDF-R Add-A-Dog Collar Receiver. The In-Ground Fence system is expandable to any number of dogs.
Collar-receiver provides four adjustable correction levels plus beep and vibrate-only modes
"Anti-linger" feature on collar keeps dog from constantly testing the boundary
Low battery indicator