Material: Caster sleeve is made of PP/PA material, and strong, not easy to be , can be used for a long timeDimensions: Our overall length of the caster sleeve is about 43.5 mm (1.71 inches), the diameter is about 25 mm (0.98 inches), and the hole diameter is about 11 mm (0.43 inches).Compatible with 7/16 inches stemsWear : Black caster rod insert sleeve protect chair legs and floors from wear and tear. Plastic caster sockets mount securely to the chair legs and are not easily droppedEasy Installation: These plastic caster bar socket insert covers are very easy to install and remove. Perfect for all kinds of universal casters. Great protection for your universal castersPackage Includes: 40pcs plastic caster sockets. Caster stem sleeve parts for casters of chairs, tables, bookshelves, filing cabinets, machinery and moreColor:BlackMaterial:plasticPackage Contents:40 * Caster Socket