Purchase info: Kuryakyn Universal Throttle Boss. 6251. Installs in seconds according to the insructions however I had to use two pieces of velcro between it and the throttle to keep it from sliding around.
Please be aware that this Mod has the potential to seriously upset your control of your bike when you hit a bump especially in the beginning when you are learning how to use it. If you have already mastered your throttle control, you will most likely be able to learn to use this throttle Boss. DON'T use it if you are still accidentally cracking the throttle open.
I have a Crampbuster on my ST1300 and one comming from Amazon for my Hyabusa. I like them, relieves the tension in your hand and wrist.
The Cramp Buster (?) is Kydex or PVC and fits onto the throttle just like yours. I also have a Vista Cruise to lock the throttle in position too. I'd like a true cruise control but that's not something I want spend $500 to $1000 on.