EPGardening Black Natural Resin 4 Wheels Plant Caddy/Dolly(12.5") Outside diameter:12.8",Inner diameter:11.8" Made of latest PP resin,environmentally friendly,safe,durable Wheel plug is striped,more stable to catch chassis Thickened material,sturdy and stable.Smooth surface,easy to clean Designed with universal wheels,easy to move and rotate,sturdy and durable,not easy to scratch your floor