Simply unbelievable. Some reviews made me buy two of these just to be on the safe side and make sure I can get the job done if one breaks or works. It drilled all 12 holes in my cast relatively easily the first time. Still about 3-4 times harder than drilling a hole in drywall, but doable. Gypsum wasn't just wire mesh. it was on an expanded metal screen used for ceilings. The hole saw was perfect and still very sharp so I will be returning a second one.