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There are two ways of connecting devices to the optical path of the AP26-series cameras:
The M42x0.75 interior thread
This interior thread works well for attaching filter wheels, telescopes, filter holders, etc. If your device has a different diameter/thread, you may be able to use a thread adapter.
The six small holes with M2.5 threads
These six holes are distributed over a circumference of 62mm of diameter line up. They have an internal thread, M2.5. These holes line up with the holes on the ZWO 2" EFW (or the holes on the "new" 36mm ZWO EFW). They also match the position of the holes of the QHY CFW-L, but you will have to purchase M2.5 screws because the screws provided by QHY are M3 thread.
The QHY filter wheels come with six screws that have an M3 thread. You can use a QHY filter wheel but must buy 6 (M2.5) screws. Amazon sells packs of different sizes. McMaster-Carr sells them very cheap. Also, you have to select the length that you need, probably 6 or 8 mm, depending on the thickness of the wall of the filter wheel. Again, buying different screws is only required for QHY filter wheels.