What I have figured out. Most I have seen have the two part design with "registration pins" in the center section where one installs shims to vary the thickness. They all seem about the same. Question is any brand noticeably better than others ? Do most of these use generic insert cutters available at numerous sources ?The last aspect of this equation is the thickness range of the tool. I have pretty much decided that a 5or8mm to 12mm and a 12mm to 24mm are the two ranges that will probably end up in my arsenal. Which one would you purchase first ? Are these the right size ranges to cover most uses ? I will be using these for commercial work as well as furniture etc. Presently I am looking at Amana ,anyone with suggestions on which tools to look at or other brands entirely please fill me in. Thanks Mike.