This item is discontinued. Check out PetSafe Stubborn Dog Collar PRF-275.  It's the same collar receiver but with a nylon strap with a plastic clip. 

With the SportDog Electric Dog Fence Receiver Collar SDF-R, you can add unlimited dogs to your existing SportDOG pet containment system.

Just like the one that comes with the SportDog SDF-100 electric dog fence system, the SportDOG SDF-R Add-A-Dog collar has four adjustable levels of correction with a beep and vibrate only mode. The collar is 100% waterproof and submersible and includes a convenient low battery feature to let you know when the 9-volt battery needs replacing.

Compatible with these Fence Systems

• SportDOG SDF-100A In-Ground Fence
• SportDOG SDF-CT In-Ground Fence (for containment only)
• PetSafe PIG00-14673 Rechargeable In-Ground Fence
• PetSafe PIG00-13661 In-Ground Dog Fence
• PetSafe PIG00-14582 Basic In-Ground Fence 
• PetSafe PRF-3004W In-Ground Dog Fence
• PetSafe PRF-304W Deluxe In-Ground Dog Fence
• PetSafe PIG00-10777 Stubborn Dog In-Ground Fence
• PetSafe MIG00-10939 Stubborn Dog In-Ground Fence
• Petsafe MIG00-10938 Deluxe In-Ground Dog Fence
• PetSafe ZIG00-14658 Stubborn In-Ground Dog Fence
• PetSafe ZIG00-14654 In-Ground Dog Fence
• PetSafe PIG00-10773 Little Dog In-Ground Fence
• PetSafe PIG00-11007 Cat In-Ground Fence
• PetSafe PIRF-100 Indoor Pet Fence

Features

• 4 adjustable levels of static correction
• Beep and vibrate only modes to allow you to tailor your training to your dog's temperament
• Anti-linger feature to keep your pet from running down the battery
• Designed for dogs that are over 10 pounds in weight
• Receiver collar is durable and 100% waterproof and submersible
• Collar functions off a 9-volt battery with an average battery life of 4 to 6 months
• Low battery indication feature to let you know when the battery needs replacing
• One year warranty

Box Includes

• In-Ground fence receiver collar (SportDOG SDF-R)
• 1 " Black Collar Strap
• Battery for the dog collar (Standard 9-Volt)
• Short contact points
• Long contact points
• Test light tool to ensure the receiver dog collar is functioning properly
• Product Instructions