Petmate 82322 Mighty Link Chain Collar for Training Pets Guaranteed against rust, tarnish and breakage, Might Link collars are created with nickel and chrome plating for durability Choose the perfect length by adding 2-3" to the circumference of your dog's neck To be sure the collar is on correctly, allow the collar to hang down When looking at your dog, the collar should form a "P" shape Available in a variety of lengths and thicknesses