Add a second collar to your existing PetSafe Remote Trainer. Compatible with the following PetSafe Remote Trainers : PDT00-16117, PDT00-16120, PDT00-16123, PDT00-16024 and PDT00-16027. Train Up to 2 Dogs at the Same Time - Compatible with the following PetSafe Remote Trainers : PDT00-16117, PDT00-16120, PDT00-16123, PDT00-16024 and PDT00-16027 Tone, Vibration and Static Stimulation - Features three different types of stimulation: tone (beep), vibration, and 1-15 levels of static stimulation Rechargeable - Uses a USB cable for charging (included) Waterproof collar is submersible up to 5 feet Adjustable, Replaceable Strap - Includes premium coated strap that fits neck sizes up to 23 inches