These Shopping Cart Caster Wheels are made of high-quality polyurethane and carbon steel materials, with a load capacity of up to 500 pounds. Measuring 4 inches in diameter, 1.25 inches in width, and with a bore of 3/8", they feature double ball bearings for smooth and quiet operation. These versatile wheels are perfect for various applications, such as shopping carts, warehouse trucks, mobile carts, and furniture carts. They are also resistant to most chemicals, solvents, acids, and oils, making them ideal for any environment.