The SportDOG YardTrainer SD-105S has been proven safe, comfortable and effective for dogs over 8 pounds. Consistent, correct use of this product allows you to reinforce commands and correct misbehavior from up to 100 yards. 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 stimulation levels so you can tailor the stimulation level to your dog¿s temperament, eliminating the risk of over-correction.