Sparx Hockey Fire Grinding Ring 3 8" Size:3 8" The Marsblade R1 roller hockey The Marsblade R1 roller hockey chassis powered by the patented Flow Motion Technology a unique rocker that can be customized to players skating style and improves all aspects of skating The connection system allows for expansion and contraction to ensure your surface stays flat through temperature changes Sparx has re imagined and optimized a flat bottom profile that provides improved glide while still maintaining desired bite Their FIRE Ring profile is more forgiving than that of other flat bottom hollows on the market equaling a more confident feeling every time you step onto the ice