• Front side - M28.5x0.6 female thread
• Rear side - M30x0.75 male thread

Machined from high quality aluminium alloy.

This adapter is purposed to to replace the part indicated with the arrow on the diagram.  It is being delivered with a QHY 678M camera, and when coupled with a focal reducer, it causes vignetting. If you have no need for either a UV-IR filter or an IR long-pass filter, you may replace it with this shorter adapter.