The pictured item appears to be the chunky "series 2" Kobalux, which is the one that Dante and Stephen like.
Like Foto_Fool, I've got the Avenon-branded "series 3" version, which is more compact and probably even a touch better optically. I don't have anything against which to compare it except the 20mm f/2.8 AF-Nikkor; the Avenon is much, much sharper (although this particular Nikkor doesn't have an especially fabulous reputation, so that may not be much of a recommendation!)
Incidentally, for those who weren't around back then, several of us have the scarce-as-hen's-teeth Series 3 lens thanks to the fact that a couple of years ago, an Asian-based RFF member (whose identity I will keep secret) came across a cache of factory-new-in-box ones in an Asian camera store. The story was that the store's owner was a friend of the president of Kobalux, and when the firm was shutting down he had bought out the last of the inventory. Our RFF contact volunteered to serve as a go-between for any of us who wanted to buy these, and several of us got them. Just a reminder of how things were in the old days when RFF was a smaller place...