Review on GP16 8 Inch Drywall Cutting Blade Set: 16 Pack for Efficient Precision Cuts by Dwayne Calhoun

This nozzle works great if you don't let too much of the nozzle protrude past the drywall. A prerequisite for this is a functioning depth setting of the Roto-Zip. Otherwise, this bit turns into a plane and peels the surface of window and door frames. I haven't had the problem of parts breaking like other reviewers, but I suspect it's because I followed other people's advice and didn't apply much pressure. Let the bit do the cutting. They don't last forever either, so if the tip starts to stick to the flutes, it's time to toss it and get another one. I buy Roto-Zip bits in packs of 16 so they're not very expensive. Works great on plastic electrical switch boxes. again, only if not too much of the bit is sticking out. If you smell burning plastic, you're probably cleaning the box by slicing through the rock.