The MS-5 ultrasonic High Tech collar opens all High Tech Pet Door models. The MS-5 operates on a B3V1A battery, which is not rechargeable.
The Ultrasonic Collar can be programmed to work with ranges from 1 ft to 10 ft from the door. Inside and outside ranges can be adjusted independently. First, push the SENSORS button on either the inside or outside, depending on which you want to change. Then, turn the RANGE knob to the desired range from 1 ft to 10 ft.
High Tech's MS-5 collar is waterproof.
Be aware chlorine and saltwater are corrosive, meaning metals and rubbers are likely to rust and break down (i.e. pools, ocean, etc.)