Einstein ET-502 Two Dog 1/2 Mile E-Collar Remote Dog Training Collar With Vibration and Tapping Sensation Two dog system with 1/2 mile range Medium/large receiver (2.7"x1.7"x1.2", 4 oz.) for dogs 15 pounds and larger Ergonomic "stopwatch" design transmitter allows you to watch your dog at all times Education tone button provides 1.25 seconds of tone followed by stimulation (Pavlovian effect) User-selectable stimulation levels from 1 to 100 with additional boost stimulus selectable from 1 to 25