ZEISS designed the 1.25" Astro Adapter specifically for stargazers who want to use their standard astronomical eyepieces on their Conquest Gavia 85 spotting scope. Outfitted with the spotter's eyepiece holder bayonet-mount, the adapter has a compression ring and retaining screw to secure a 1.25" eyepiece.
I found out about this in some trusted only reviews. The fit is good, with no play and the lock mechanism is well thought, both for the scope mount and the eyepiece mount. It’s easy to secure the eyepiece with the screws. It appears to use small plates friction so tightening the screws should leave fewer marks on the eyepiece tube, if any at all! The only challenges is the scope mount. It is tight and easy to assemble. But it does no lock in place. It does not require much rotation to release the adapter. So if taken in the field, I have to take extra precaution. It’s probably designed to allow great flexibility and adaptability, which is why it does not allow the Gavia 85 original eyepiece lock (the ring located by the mount) to function. I also wish it came with a set of basic thumb screws for those who prefer this.