ProMounds Portable Pitching Mounds are made out of heavy-duty, high density foam and covered with skid-proof rubber armor. The combination of the foam core and the rubber armor distinguishes our pitching mounds as the most durable and lightweight models on the market today, guaranteed not to damage any gym floors. These pitching mounds include spike-resistant artificial turf (36 oz. Polypropylene Monofilament with a 5mm pad). A regulation pitching rubber is attached to every mound. Every mound has two handles on each side for easy transport.