Mine has a #2Mt and a 1/2 inch rod out the front. The die holders and the small drill chuck all fit this one holder. Mine has no slot so is free to spin if you let go. The drill chuck only holds drills to 1/8 of an inch, and the die holders suite the small series dies I have up to M10 .
Mine is nothing flash but works really well.
I also made the small drill one for milling machines, made 2 types, one that uses the range of the dremel collets, so will hold to 1/8 and the other with the small chuck that can hold to 3/16. The drill chuck one with the drive peg and return spring, is good for power tapping the small holes upto M4.
After making mine, a friend showed me the one he bought online, lol.
Mine have a 46mm travel where as the online one I saw only has like 19 mm or so. It means I can drill small holes down the centre of the con rods a lot easier.
Neil