Orion field flattener question

[Wilsil]

All,
I have been given an Orion field flattener to try on my ED80.
However there seems to be a missing part, the M48 adapter.
My new camera came with a M54 threaded spacer but this doesn't fit the Orion.
Does anyone has the field flattener and can tell me what the thread is?
I have attached a picture showing the adapter.

[Nikolas]

If I recall it's an m42 you need to get an adapter to fit it.

[Wilsil]

The thread on the flattener is definitely not M42 as even M54 will not fit.

[The_bluester]

If you mean the thread on the corrector that the M42 adapter screws on to, the next likely size might be M68 if M54 is too small.