The Aro arm rest comes as part of the package with the arm. As the arm is discontinued (sadly) I suspect the arm rest is no longer available. It might be worth your while to give Naim a ring and ask them though. I needed a set of grilles for my SL2s, which are supposedly unavailable now. My dealer made a call to Naim and a new set was found. They are hidden away until after we move house, after which the current, rather tatty set of grilles will be retired.