The PE-903 Pro Educator e collar is designed with safety in mind. The maximum stimulation setting and lock and set guard against accidental overstimulation of the dog. Even with its small size (2"x1.5"x1"), it provides plenty of stimulation, even on 150-pound dogs. Our pro training collar is equipped with a night tracking light to easily locate the dog after dark. Let the Pro Educator E Collar help turn your stubborn dog into an obedient dog!