Discovery was designed with smaller children and unique indoor environments in mind. This is not a discussion of durability, as this is as durable as they come, but the use of soft XP fibers, constructed in a short, dense product (with a thatch) means there is no need for infill. Kids can't put it in their mouths or get it in their eyes, because it isn't there. Discover the finest in playground surfacing with Playground Grass Discovery.