It's a type of propane (LPG) carburetor if you've never heard of it, designed to run engines properly on LPG, without all the problems associated with mixer rings, and without the expense of LPG injection.
I've done a search for "BLOS" on here and it doesn't seem to bring up anything relevant.
Although it's a simple low tech, non electronic device, it was apparently developed for use on fuel injected engines, (although used with success on carburated engines too), so I would have thought it ideal for the "Anvil" jeep 4 litre as fitted to most XJs, YJs, and TJs at some point.
Basic units are on eBay from £105 (I bet that has got your attention)
So is anyone on Birtys running one yet
I'd like to know if all the positive write ups they get are justified.