I have had this kit for over 2 years now and have used it many times on wood, MDF, drywall and several times on metal both by hand and on a drill press. As usual with this type of simple bimetallic hole. Saws, don't expect miracles - they will cut through almost anything but leave no smooth surface, get very hot and it can be painful to remove the washer from the saw. Hole saws are almost the same and have the same mandrel size so they are interchangeable - you won't notice any difference…