Series 2 - New collar sizing, if you have purchased this same collar before, please measure your dogs neck to ensure a correct size. Suffering from sensitive skin? This collar consists of 3 internal layers: nylon, foam & neoprene. When combined = exceptional comfort for your dog, a collar that can be worn all day long and is great for dogs with sensitive skin/fur. Suitable for ANY breed type. Thousands of people have experienced a much more pleasant walking experience only after the first walk with this type of collar. Made with two Stainless Steel D Loops, the larger is slipped over your dog's neck, while the lead is clipped to the smaller. When your dog pulls, the tension pulls the small loop taut, which tightens the larger loop on the neck. This collar also comes with two reflective strips to ensure safer and visible night walks. For a larger head, the next size up may be suitable.