What’s the difference between 23.5, 25, & 25.4mm versions of the CNC Machine?
See the previous 3 links I sent as well as this.
You might just want to look through the menu for all the details.
Depending on where you live, commonly available electrical conduit is not always the same outside diameter. You need to find out what kind / size of tube you are going to use and then print the corresponding set of parts. I went with Stainless tubing that was 1" outside diameter. So I bought the 24.5mm parts set (I didn’t have a 3d printer at the time).