the one I got is without the glass so you loose infinity focus, I purchased it from adorama. I have mostly just been using it for macro things, I decided today that I wanted one with the glass so I ordered that this morning so that I can do some more distance shooting and just compare the one I bought today is this one and if I had better neem paying attention the first time around I would have probably purchased it instead of the one from adorama because it looks like the glass is easily taken out of this one so that you can use it either way. So far I have tried it with 2 different 28mm lenses, a 50mm a 70-150 and a 70-210 macro. All of them have worked out pretty well. The short lens have a very small focassing distance we are talking like 1 inch to 3 inches the long lenses around 1 through 8 feet. so for macro this is great (which is why I bought it) so I cant say how it will work with the ones with glass yet, but either way it was worth the 34 bucks to use my old lenses. So I would say its deffinatly worth the money espesially if you already have lenses laying around. I did do a bunch of reading and it seems athough lots of people nay say it they havnt actually tried it and those who have say they have good results.
ok so hope that made sense sorry to ramble on