Those are some other kind of shank, but yeah thats the general idea. Here's a link to the one I use: http://a2zcnc.com/products.asp About mid way down. A different one is necessary for every size end mill you plan on using. I've been getting by with just a 3/8" as thats a pretty common shank size (even for small cutters, down to 1/8") and I wouldn't recommend using end mills larger than 1/2" on a stock Taig. I use my 1/2" arbor for a tap holder and things of that sort.