Fairly dangerous. I had two rolls of sandpaper that came apart at the seams and flew back at me. These are basically flat sheets of sandpaper "rolled" onto a backing cloth. I didn't touch anything, I just turned my drill on with the drum in the chuck and tripped over it just to check the rotation. Kids, I remind you, always wear a face shield when operating a power tool. The first roll of sandpaper was spinning at a few hundred RPM and hit the guard in my face. I could lose an eye. The second spun and hit my hand, luckily I was wearing gloves. I dropped all the unrolled sandpaper and went to Menard's for what appeared to be from a reputable supplier.