They don't have them individually on the website, but if you look at the packages they do for the Rocket, clutch springs are included.
If you phone them they will hook you up.
When I put the Stroker kit in my otherwise stock engine, it made more torque at 2000rpm than the standard Rocket III or newer Rocket 3 do at peak. Anything over 50% throttle and the clutch slipped.
Phoned Erik in Carpenters and I had a set of their springs the next working day (
I'm in Ireland - sent Friday from USA, arrived Monday in Ireland).
These are the strongest springs I've heard of for the Rocket.
They still hold up now to my 2.5L Supercharged Carpenter Stroker anyway....
Oh and if you're putting pressure on your clutch, best replace the spring tower bolts too with 50mm long ones, because;