... crumb rubber, and bottom is black big crumb rubberThSE RUBBER BRICK have some predominant capability, elastic, water-proof, slip-resisting, ... training ground and other public places.Features of rubber brick:1.playground flooring rubber brick2.Suit for schools,parks, ... , acid and alkali resistance, auti-aging, environment-friendly, no joint, easy to maintain.6.Usage: children playground, tennis court, ...