Baader make the combo from their Hyperion Zoom eyepiece and the 2.25x Barlow designed to go with it, but you can buy the two separately (although it may be cheaper to buy together). The combination results in eyepiece focal length equivalents of 3.5mm through to about 10.
Naturally they suggest it works better with their eyepieces
but I use mine with a Panoptic and a couple of ES 82s when travelling, as the scope has a short focal length.
Given your main scope has a relatively long focal length, I'd say your get practically no use from using one with your 9mm eyepiece. You might get more use out of a 7 or 8mm eyepiece, but it's a bit close to your 9 IMO.
Are your eyepieces the one that came with the scope?