The tool post collar works on any tool rest that has a 1″ diameter post. They are used to set the height of your tool rest at the lowest position that you normally use. This allows you to only have to adjust a small amount each time for different tools, rather than having a large range to have to adjust. For Trent it is a must have on each one of his tool rests as well as on his Stabilizer’s (which it comes standard on).
Trent also uses this collar on his grinding set up, see details in this video if you think this might be right for you.
Make sure you specify how you will be using the collar.