First, the negative reviews are true! This hole saw comes with a non-locking mandrel. Newton's first law of physics tells us that a moving object will stay in motion unless some other force is acting on it. Let's think about that for a minute. The hole saw spins insanely fast at the tips of your hands and probably very close to your face with a lockless shaft = as another review puts it, a "spinning deathtrap"! When the drill stops, the mandrel stops, but nothing interferes with the rotating JAWS teeth. Again, Newton's first law tells us that it will keep spinning until you just can't stop catching it. Other reviews describe the results of this scientific experiment. So if it's going to be sold like this, NO! This hole saw has holes for installing locking pins. Buy a stop mandrel like the one shown in the picture. All the big stores sell them and I'm sure you can find them at Revain. Do like me, drop the bits and toss the wave on the scrap heap. I only bought a 60mm hole saw because the crazy 6" LED lights I bought on Amazon were almost 6.25". If you don't like paying $90 for a name brand hole saw that you only use once or twice, this is the perfect product. Cuts well and cleanly. I had no problem going through 1" pine and 1/2" plywood to mount my lights. Like any hole saw with that many teeth, it easily hammers into pine or softwood. You'll get annoyed if you stop brushing your teeth, but I have expensive name brand hole saws that are much smaller and do the same thing in softwood. I've included a picture of a hole saw with the arbor that comes with the kit and the arbor I already had for branded hole saws. It just screws in and the pins align. So if you just don't want to defy the laws of physics, I highly recommend you buy a better mandrel or search your toolbox and find the right one. Highly recommend this product unless you are a professional electrician who installs lights all day. If that's the case, buy a $90 carbide hole saw from a reputable brand.