The Alterra has standard handle bars. So the Kimpex one should work, it any other really.
I'll say this though, think about it, you're riding some bumpy terrain and how much your hand is going to move, are you going to be burping that throttle like mad?
Another option is the Kimpex thumb extender, my wife loves it. I hate it, I've gotten a sleeve or glove stuck and locked in full throttle. Once almost hitting a tree, and another time I ran the dog over. So that thing is in the trees somewhere now lol.
I'm saying be careful, try it in a safe place and make sure it is safe.