| The rear sprocket is a pretty large piece of metal. It carries the cush drives, unlike "conventional" sprockets.
This is what makes them so much more expensive.
Renthal do a conversion that essentially splits off the centre assembly, with the cush drives in, from the sprocket.
This means that once you have the carrier in place then the sprockets are changed in a conventional manner and at about the same cost. Much easier to as you don't need to remove the carrier assemblt from the hub.
I don't have any in stock at the moment. I can get them within a couple of days or you can go directly to B&C Express who distribute them. | 
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