Strimm Humane Training Half Semi Choke Soft Leather Chain Dog Martingale Collar for Control Small Medium Large Breed Dog-Brown/Black Suit for medium sized dogs,Width:2.0cm; Neck adjustable length: Minimum: 35cm, Maximum: 48cm 100% imported genuine leather material, stainless steel chain, anti-rust A wonderful and more humane way to train and walk your dog It's a great and more humane alternative to prong/pinch/full choke collars that can cause throat damage over time It allows you to have much more immediate response when walking, without actually choking dogs like a full choke collar would do. Another great benefit is eliminating dog's ability to back out of a collar as it tightens just enough to prevent it