I bought 4 of these windows to replace 1957 single pane, iron frame, basement windows. The widows are double paned, without argon gas, but argon doesn't do much. Installed, they look beautiful, and they will be great for the next century. Beware when opening the package, because the removable window is ready to take out, and if your not careful, it can drop on the ground. Also, critics gig the window for its plastic lock and lack of a handle (to slide the window open), but don't worry. It locks great and the window opens and closes easily. I couldn't be happier (I bought 4, and even got a 15% discount). As a do it yourselfer, make sure you use the right tools:\nA saws all ($199) with a metal cutting blade (to cut out the metal frame).\nA mallet hammer and two chisels (one for close cuts, and one with a 3" flat blade, to even out the concrete).\nA high-speed concrete (hammer) drill, with a 1/4" masonry bit, to make holes for concrete screws.\nTapco concrete screws (1/4" x 2 1/4"), 4 per window.\nA small, 1 foot long level, to square the window.\nA thin black marker, to mark holes before drilling.\nYard work gloves (to protect your hand when chiseling). \nPlastic safety goggles (a splinter can change your life).\n\nThat's it, my friend!