All Collar Charms are hand made in the USA using Makin's Brand® Clay. A specially formulated air dry, no bake, polymer clay, it is safe for your pet and is guaranteed not to break. Sizes for collar charms are designed for different breeds and how they may fit on your collar. Custom designs are available (please see Custom Charms for Pricing) in a variety of colors. Please contact us with any questions on our Collar Charms.