The Rubit Dog Tag Clip is a simple, stylish, and secure clip that let's you swiftly transition your dog's tags to different collars. Rubit's goal is to create a product tough enough to take years of trips to the dog-park and to create a unique and simple design dog owners will love. Pick the color and size that you like. Available in 3 sizes: Small 21mm/0.85-inch (about the size of a nickel) - Fits most D rings on 5/8-inch and narrower collars Medium 27mm/1.07-inch (a little smaller than a quarter) - Fits most D rings on 3/4-inch - 1-inch wide collars Large 33mm/1.3-inch (about the size of a quarter) - Fits most D rings on 3/4-inch and wider collars . You will quickly appreciate and love the Rubit! Dog Tag Clip.