The Warren London Glass Pet Nail File is made of Sandblasted Tempered Crystal Glass which smooths nails without wearing down. Strong enough as a Dog Nail File For Large Dogs, and it's compact size works well as a Dog Nail Filer for Small Dogs. Easy To Use- Simply rub this crystal dog nail file board on the edge of your pet's nails to wear down the rough edges. The perfect tool to smooth the rough cuts after using Dog Nail Clippers or Dog Nail Trimmers without the risk of cutting too deep. Durable & Safe!- This dog nail scratch board will not wear down and is among the dog nail care products that you will have for years to come. The tempered glass makes this crystal nail board for dog nails safe to use without the risk of breaking.