The name if he company is EFK Firedragon. They have only recently added the CZ barrels to their listings. The last time I checked they only offered the standard 9mm replacement barrel. They assured me several months ago they planned to have both the 9mm and 357 Sig barrels for the CZs about last June. But a followup indicated they were having problems getting the materials needed, and anticipated they would release the 9mm barrel first, to be followed with the others later.
Once I have their 357 Sig barrel in hand for my 75B 40, and have confirmed it works as expected, I will let folks here know for sure.