Made of PU and zinc alloy material, they can be used for a long term. Transform your flight cases, instrument cases, display equipment, dollies, tool boxes, light machinery, and furniture into practical pieces that can be moves with ease using our caster wheels! Easy to use and practical, these heavy-duty caster wheels are must-haves for many projects. Features - Material: PU, zinc alloy. - Size: 8.50X4.50X2.50cm/ 3.34X1.77X0.98inch. - Can be applied to most chairs such as office chairs and computer chairs. Rather universal use. - The design is simple in structure, easy to install. Very practical for home use. - Made of zinc alloy and PU material, enough for your long-term use. - With environmental protection, universal wheels can bear strong and wear-resistant. - Making your chair more convenient and labor-saving to move. Enjoy and smooth gliding at your home or office. Package list: 5 x caster wheels