I'd ask the seller for the serial number found towards the top of the reservoir. With the serial number Elka would be able to tell you the weight and type of riding they are valved for. They would also be able to tell you what size A-Arms they would fit on. I thought about buying a set of "Dune Edition" shocks on line about a month ago, but just decided to bite the bullet and go with a completely new setup that consists of Elka stage 2+R Long Travel front shocks and Roll Design Long Travel A-Arms (Desert, MX, Dune Edition) after speaking with Eric from Elka Shocks at the last Sand Sports Super Show in Costa Mesa, Ca. FYI-I do 50% desert and 50% dune riding.