Leatt's much-anticipated 5.5 and the latest 4.5 GPX Motocross Helmet's offer groundbreaking head and brain protection!. We all crash. Sometimes hard, and sometimes even harder! There is a solution to minimize the risk of a head and brain injury, however, and that is to get the best helmet out there that can reduce both rotational acceleration and impact energy to your head and brain. You cannot deny that Leatt is committed to rethinking and improving products that have been the same for years.