This is a collar that slips into the 'scope body and is held in place by a screw-on ring to form a 1 1/4" socket and thus allow the use of third party eyepieces with a Zeiss scope. You can alternatively clamp it onto the 1 1/4" eyepiece tube, sandwiching the locking ring to make an assembly that holds the eyepiece securely. Not cheap - but neither are Zess 'scopes. It is as well engineered and finished as all Zeiss products. The only thing is that is doesn't work properly, at least with Baader Hyperion eyepiecs (I have not tried other makes). The thickness of the locking ring means that the eyepiece stands further out of the scope body (in my case the 45 deg model) than without the ring. This places the focal point of the eyepiece further out of the tube than without the locking ring, and in my case it meant that the 'scope could not be brought to a focus for objects on the horizon / infinity. Focussing was ok out to about 400 yards. Remove the locking ring, and it was ok as the eyepiece was deeper into the scope body. I have e-mailed Zeiss to enquire whether this is caused by my scope not being adjusted properly (very unlikely) or whether it can be tweaked by the service department here in the UK but have not got a reply. The fact that it doesnt work properly is a real nuisance as Zeiss offer only the zoom and a 40x and neither can be used with a screw-on camera mount for digiscoping because of the eyeguard. There is however another and excellent solution to using fixed-focus prime eyepieces of mid to low powers with the Zeiss Victory. Baader make a compatible bayonet adaptor that clamps onto the 1 1/4" tube. I have tried it with the 17, 21 and 24 mm Hyperions. This pulls the eyepiece snug against the screw ring and is a much better solution than the Zeiss acessory. The only thing is that you need one for each eyepiece, but you get the full focussing range.
Pros: Excellent quality
Cons: Moves the eyepiece too far out of the tube - can't focus at infinity
This review was written in the old system and had content requirements that are different than reviews written today.