Hi Angela, If they say it's 4.05, then I guess that's what it is. The CD's were 4.04 last month. I have to wonder what they're doing with the ones they don't sell, LOL! Personally, I find 4.05 to be the best so far. It still has a few minor bugs, but nothing too bad. The newer Poser .bum files will load, and the volumetric lights are far better than in the initial release. It seems more stable, and seems to render faster than 4.0, as well. I like it. :)