I have both sitting here side by side and the phiniac reg is too wide and too short, the phiniac xl will be too wide and too long. there is a company called IBTanked, that make glass tanks and they seem a bit narrower and longer, you might try them out and see if they give dimensions. But like Tangier said, the pyrex tanks are not threaded but sort of rounded and smooth. It would be real nice if they came with pyrex custom tanks. I already noticed my vivi nova tank has dulled alot, Ive only had them over a week. I did get the aluminum replacement tank and it its quite nice and of course wont get messed up by juices. Only down side is that you cant see your juice but I havent had a hard time telling if it need filling. I just start to notice I keep having to swish more than usual and I untwist the top and look down and fill.