Pronged, linked design is gentle but effective in enforcing pack leadership. Helps prevent pulling and lunging behavior. Has appearance of a flat collar. New Available in Small and Large sizes. Linked “watch band” design allows for sizing adjustments. Additional links sold separately. Small – 15" Large – 21" The Pro-Training Collar should fit snug, but not tight, around your dog’s neck. You should be able to fit 2-3 fingers between the collar and neck.  If the collar can slip over your dog’s head, it is too loose. Gentle & Effective Pronged, linked design is gentle but effective in enforcing pack leadership. Helps prevent pulling and lunging behavior. Has appearance