Upgrade your ride with the HJC i50 RED BULL SPIELBERG off-road motorcycle helmet in the striking blue-red / MC21SF colorway! Available in the following sizes: extra small, small, medium, large, extra large, double extra large. HJC i50 RED BULL SPIELBERG Off-Road Motorcycle Helmet - Blue-Red / MC21SF. HJC i50 Red Bull Spielberg Helmet. The HJC i50 uses SLID (Sliding Layer Impact Distribution) technology that helps to redirect energy-exerted impacts on the brain by reducing rotational acceleration caused by oblique impacts. SLID is located in the helmet interior and is an advanced gel ...