The 10mm collars are for use with the 10mm letters and charms and come in a variety of colors and materials, to suit every type of dog! 10mm Patent Leather Collars 10mm Velvet Collars Sparkle Dot 10mm Collar Glitter 10mm Collar Metallic 10mm Collars Croc 10mm Collars (pink) Leopard 10mm Collar Denim 10mm Collar Camo 10mm Collar Sweetpeas Posh Pets