Astromania M42X0.75 Female to M42X0.75 Female Thread Telescope Adapter. M42X0.75 female thread on both sides. This is a very high quality anodized aluminum adapter. Converts an M42X0.75 male thread to a M42X0.75 female thread. All metal construction and anodizing aluminium process, durable for long time use. Makes it possible to attach M42X0.75 male thread and M42X0.75 male thread accessories together. Such as, you can upgrade your R&P focuser by adding "Astromania 1.25" High Precision Double Helical Focuser" to the end of the R&P focuser, if there is M42X0.75 male thread on the R&P focuser. this adapter will play very important part in connecting "Astromania 1.25" High Precision Double Helical Focuser"and R&P focuser.