The SportDOG SportHunter 1825 has been proven safe, comfortable and effective for all dogs over 8 lb. Consistent, correct use of this product allows you to reinforce commands and correct misbehavior from one mile. The remote transmitter sends a signal, activating the collar receiver to deliver a harmless stimulation. With proper training, a dog will learn to associate this signal with a command. Like all SportDOG products, this model features adjustable static stimulation levels so you can tailor the stimulation level to your dog's temperament, eliminating the risk of over-correction.