This is the world's first machine which forces you to stand and balance while building strength specifically for cross overs. The Lateral Crossunder attachment and double crossunder attachment allows users to build strength, power and quickness in the crossunder movement pattern. You can see this movement pattern in a variety of activities beyond skating. The Lateral Crossunder Attachments are a must for all skaters, but athletes from any sport which requires changes in direction will benefit from this type of training. This heavy-duty steel platform fits underneath either track for left or right exercises. Easy to position, installs in seconds.