Zinc plated, double ball bearing raceway. This is a great caster for office chairs, carts, mop buckets, etc.

Non-marking thermoplastic rubber tread is mechanically bonded to a polyolefin core, and is great for clean enviroments. It is a light weight wheel with good capacity. Is highly resistant to oil, grease, water and most solvents. This wheel has great floor debris deflection with smooth quiet rolling.