A quick look at Baader Hyperion Zoom Barlow
Baader Hyperion Zoom Barlow is a lens designed for Hyperion Zoom eyepieces, but can be used with other or with planetary cameras. It's a 3-element design, but different than typical 3-element APO Barlow. The design is told to be anastigmatic. The last lens is strongly convex (be careful not to scratch it) so it does differ from normal lenses. When used with Hyperion Zoom eyepiece it gives 2.2x magnification increase.
With the lens you will also get a 1,25" extender-adapter and T2 adapter. The lens assembly has a 1,25" thread and no collar so it can be hidden withing a 1,25" eyepiece holder. The 1,25" extender-adapter works as a collar - it gives 1,25" thread, but can't be hidden withing a 1,25" eyepiece holder. The T2 adapter works in a similar manner.