Another EMS-UL SET in the making

The D is the most important measure when you order the EMS SET.
The change of the D will not be accepted in the course of making.
The standard D of EMS-UL with IPD-Helicoid is 160mm.
If you change it to 172mm,for example, the extension tubes should be added and the three set screws at the end of the first unit will be dummies.