1.Material: Our metal dog collars are made of high quality metal and are durable and rustproof.2.Adjustable: Our metal dog choke collar is equipped with practical metal rings so it is easy to adjust to your dog's neck girth, making your dog more comfortable to wear.3.Size Available for Different Breeds: The width of this training dog chain collar is 2mm(S), 3mm(M), 4mm (L)gauge link, and 3 length S Length: 15 (suitable for dog's neck within 11"),M Length:21(suitable for dog's neck within 19"), L Length: 25 (suitable for dog's neck within 21"). Please kindly using soft tape to measure your dogs head and neck to choose the proper size.4.Suitable for training: Our dog necklace can be adjusted arbitrarily, perfect for daily training use.5. Safe and Firm: Our dog necklaces are made of metal and are not easy to break. The surface is very smooth and will not scratch the dog's skin.