RUFFWEAR - Knot-a-Collar Reflective, Low-Profile, Adjustable Dog Collar UNIQUE DESIGN: The Knot-a-Collar low-profile design provides a clean and elegant climbing-inspired solution for an everyday collar. It is constructed from 7mm thick rope and is designed to settle comfortably into your dog's fur and reduce matting. The collar also features reflective trim that helps you keep an eye on your dog, even in low-light visibility environments. CUSTOMIZED FIT: The Knot-a-Collar features sliding fisherman knots that allow you to achieve a personalized and comfortable fit for your dog. The anodized aluminum belay plate allows for non-slip adjustment. SECURE LEASH ATTACHMENT POINT: The Knot-a-Collar offers a secure leash attachment point via the single-piece, anodized aluminum V-ring, making it easy for you to attach a leash to the collar for walks. SIMPLE ID ATTACHMENTS AND SILICONE TAG SILENCER: The Knot-a-Collar features Ruffwear's Quick Ring technology that allows you to use the separate ID attachment point to easily add or remove tags from your dog's collar. The silicone tag silencer is built to reduce the amount of jingle in your dog's collar. Enjoy some peace and quiet as you hear only the amount of jingle that you need to hear. KNOT-A-COLLAR SIZING: The Knot-a-Collar is available in 2 sizes (see images for sizing chart): Medium: 14-20 in (36-51 cm) and Large: 20-26 in (51-66 cm). Select the correct size based on the circumference of your dog's neck. Measure around the neck where the collar would comfortably lay.