matrix extending side tray , this side tray is brand new and never been used [ it still has the foam protectors on the knuckles ] the only reason it is listed as new other is that the 30mm extending support legs are MAP legs not matrix , this has no effect at all on using the tray and if im honest the MAP legs are sturdier than the original matrix legs . The side tray will fit all 36mm seat box legs plus it has the inserts included to fit 25mm seat box legs , you can fit the side tray onto your footplate leg and the 2 seat box legs so it is super sturdy over the 3 legs or you can just fit it over the 2 and its still sturdy .