In 1960, Elbonia set out an RFP for a new carbine for a fledgling paratroop brigade. They wanted a rifle to provide a higher volume of firepower for these troops, rather like the intention of the FG42 in German WW2 service. What they got was actually based on surplus Czech vz52 rifles, adapted to use AK mags and drums, chambered for 7.62x39mm, and fitted with a flashy-looking ventilated barrel shroud.
The true story behind this rifle is still a bit of a mystery to me. As I said in the video, I have seen 5 or 6 of these in the US, some in person and some in photos. They do not appear to be a legitimate military or police configuration, and I have been able to find nothing to substantiate the rumor that the were used by Czech police. I suspect they were a fun project by someone her win the US in the wake of the early importation of vz.52 rifles. Since the 7.62x45mm ammunition those rifles used was effectively unavailable, rechambering them for 7.62×39 was a popular idea. I have not found any indication of who actually did these, though. Note that they lack import marks because those were marked under the muzzle of the vz.52s, and that part of the barrel was removed.