there are two on unicycle.com
which one is the best? I have a chrome torker, but that may change.
Also, what else do i need for changing some crank arms? I’m going from 5" to 4" for distance riding so what do you think would be best?
I like the second one (the Park CWP-5 Crank Wrench and Puller). Get it and a 6 inch adjustable wrench and you’re good to go.
The crank wrench with the blue handle has a problem with shorter unicycle cranks. With short cranks the handle can’t spin all the way around in a complete circle without running in to the pedal, so you need to remove the pedal before you can remove the crank.
The Park CWP-5 crank remover doesn’t have that problem because the adjustable wrench is not permanently attached to the crank remover. There is no need to remove the pedal before you remove the crank.
The Park CWP-5 also has an integrated 14mm socket so you can remove the retaining (fixing) nut. Quite handy.
I have the one with the handle. It works great, but like John said you must remove the pedals to use it. I wish I got the other one.
Hope this helps.
Don’t forget to remove the nut before you try the crank puller.
Daniel
Yes, and don’t forget to put the crank puller on tightish before trying to remove the crank…I’ve stripped a thread that way. I felt so stupid. 
Andrew
Go for the CWP-5. I use it and a stubby wrench. I like not having to remove my pedals