them. Shock collars Shock collars (also called e-collars, remote training collars, electric collars, zap collars, or hunting collars) are electronic training aids developed to deliver a low intensity electrical signal, vibration, tone, or light signal to the dog via the collar. They are used primarily as a means of remote communication and widely accepted as a primary tool for the training of deaf and working dogs. These consist of a radio receiver attached to the collar and a transmitter that the trainer holds. When triggered, the collar delivers an aversive. The specific aversives vary with different makes of collars. Some emit sounds, some vibrate, some release citronella or other aerosol sprays, some apply electrical stimulation. A few collars incorporate several of these. Of these, electrical stimulation is the most common and the most widely used. Early electrical collars provided only a single, high-level shock and were useful only to punish undesirable behavior. Modern electrical collars are adjustable, allowing the trainer to match the stimulation level to the dog's sensitivity and temperament. They deliver a measured level of aversive stimulation that produces a wide range of sensation, from a mildly irritating tingle or tap sensation to severe discomfort or pain. Collars startle without risk of producing permanent physical injury when used correctly. Shock collars are prohibited or restricted in some places. Attaching a leash or lead to an electronic collar can pull the contacts too close to the dog's skin, causing lessened effectiveness of the collar and discomfort. Humane bark collars There are dog bark collars that use a combination of vibrations and sounds. In several studies bark collars have been shown to be very effective. Because there are so many underlying reasons for your dog to bark, a collar may or may not work for your situation. Prong collars Prong collars, also called a Herm Sprenger or pinch collar, are a series of metal links that fit together by connecting through blunt prongs that point inward toward the dog's neck. The design of the prong collar incorporates a chain loop connecting the ends of the prong series, such that it has a limited circumference (a martingale), unlike choke chains, which do not have a limit on how far they can constrict on a dog's neck. The leash attaches to this chain section. There are two options on the prong collar for leash attachment, the dead ring and the live ring.