DESC: Ensure the safety of all your pets with these additional receivers. The lightweight, waterproof receiver is incorporated into a comfortable collar (adjusts from 6" to 28" and is not recommended for dogs less than 8 lbs.) that runs on a 6-volt battery module. Receivers have three levels of stimulation and a tone-only mode. Measures: 2-1/2" x 1-1/4" x 1-1/4". Weight: 4 oz. Electronic Dog Equipment Accessories