3 Inch Dia. 12-Pack Clear Glass Furniture Coasters/Caster Cups by A29 DURABILITY: This solid clear glass caster are made of high quality glass providing years of effortless rolling and durability. It can be screwed directly into the furniture leg. DIMENSION: Diameter Wheel:Outer Dia.: 3", Inner Dia: 2 1/4", Height: 3/4", Depth: 1/2", but can fit both broad and narrow furniture legs. On your skinny furniture legs, these coasters are best use to prevent deep indentation from forming. Please refer dimension sketch in images section. This item is sold as a Set of 12. CLEAR GLASS FINISH: These casters consist of an Clear Glass Finishing which adds an extra edge to your furniture. They are designed to protect carpets, tiles, slates and other soft floors while keeping smooth and quiet rolling.Mounting hardware such as screws are included in the package. UTILITY: These HANDMADE caster do have variations in the size and shape. However, all efforts are made by the craftsman to keep the pieces as consistent as possible. They are commonly used for small equipment and small space furniture including coffee table, plant stands, bookshelves, shoe bins, toy bins, shopping carts, workbench, underbed storage etc. SAFE FOR ALL FLOOR TYPES: These caster can be used for all floor types keeping safe your expensive wooden floors without any scratch or mark. So feel free to finally toss that study tables chair floor mat!