These 4 position racks fit the entire Transatube and Maxi Transat line. They are sold in pairs. To replace your old racks (3 positions), attached by 2 rivets: 1) Remove the 2 rivets with a drill 2) Enlarge the 2 holes Ø15/64 with a drill Ø25/64, only on the side where the rack is inserted (do not drill through) To replace your new racks (4 positions), the installation is very simple thanks to their integrated screws.