Cooey 82 peep sight thread size?

[Bigbubba]

anyone know the thread size on the peep sight for a Cooey 82?

is it 12-24? or 12-28? or other?

thank you

To clarify - it is the peep sight shown here - shooter is looking through the aperture that is threaded and held in place with the square nut on the back

 

[KotKotofeich]

If there's a way to measure, let me know and I'll try.

 

[ranman50]

The eye cup that screws into the square backing nut has a .209 diameter and 40 threads per inch.