I've only recently learned about this (apparently) short-lived project. Phrobis was best known for designing the M9 bayonet and other knives, although they had some talented engineering folks on staff.
I'm guessing this was a solution looking for a problem? Maybe at the time it was seen as a viable product due to the M9 slide breakages in the late 1980's.
Evidently, the surviving examples (of which there are very few) command prices in the $thousands.
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