About this item Perfect for Large breeds. 3 adjustable sizes: Small (5/8 inch width ,12-16 inch neck-Max 40cm length), Medium (3/4 inch width, from 16-20 inch-Max 50cm length), Large (1 inch width, from 20-26 inch-Max 66cm length). Noted: Please measure your dog's neck near the top portion and be sure to press down through all its fur to get an accurate measurement. It will be bigger than normal collars because there is an extra pull ring. Personalized and Reflective: Highly reflective strips keep your dog more visible and safer at night walking. Customized with Pet's name and phone number will be embroidered on this martingale collar. Long-lasting identification. We use a stainless steel chain that won't rust and O-ring and a sturdy nylon snap buckle. Pet's name/phone number probably be covered by the slider - The beginning of the first embroidery character will be somewhat fixed, so sometimes the name/ numbers will be partly covered if you adjust this collar to the smallest length, which does not affect daily use. Ideal for training, Martingale dog collars give you delicate control over your pet. Intended to be escape-proof, this collar slips over the head and fixes when pulled. Great for training: This martingale collar tightens if the dog is pulling on a leash. You can give your dog slight corrections and it will respond much better than if it were wearing a regular collar. The personalized martingale collars help others contact you if your pets get lost.