Innotek Two Dog Basic Trainer Train 2 dogs from 1 unit with this convenient training system Water-resistant transmitter with tone/no-tone stimulation 4 stimulus levels for each dog; 10-second lockout prevents over-correction 150-yard range; low battery indicators; collars fit neck sizes 8 to 21 inches Receiver measures 2 by 1-1/4 by 1-1/2 inches; transmitter measures 1-3/4 by 5/8 by 3-1/2 inches; limited lifetime warranty