This is an end cap for the Orion ED80, to create a "cross" diffraction pattern on bright stars for astrophotography. Other telescope designs, such as my 10” reflector, will give you this pattern by the nature of their design. There are certain targets though, which needed the short focal length of my APO refractor, but looked nicer with the diffraction pattern. The Pleiades and the Orion Nebula for example. I'm sure this would fit other ED80s, like the one from sky-watcher, but i can not confirm this.

I’ve included a couple of example pics using the printed part. Both the Pleiades and the Orion Nebula were taken on 11-9-19, unguided with the Orion ED80 on a Sirius(HEQ5) mount using an unmodified Canon T3i(600D) with APT managing the exposures. Also, these were very quickly stacked using DSS and levels adjusted using Gimp. I skipped out on post processing, using darks, flats, and bias frames to quickly post these examples with the part. So please forgive the noisy images. I know they need to be fixed;-)