https://www.bassmute.eu/bm_mainframe.html (https://www.bassmute.eu/bm_mainframe.html)
Is this the one you are thinking about? and yeah I doubt it would fit many alembics except maybe an Excel or other model with a single pickup in the P bass spot.
https://gruvgear.com/products/fump (https://gruvgear.com/products/fump)