So I was thrilled with this hole saw for a small project I'm working on. And he did a good job cutting some 180mm holes in the plywood. The problem is that the center drill stand is simply screwed directly into the saw part. There is no locking mechanism whatsoever to hold this middle section together with the saw section. So I'm happy to drill a big hole it's a hole saw so it takes a little time to cut through and voila nice clean hole and what do you do? Release the trigger! Enter the physics now! They have 180mm of heavy metal spinning in circles at fairly high rpm. And the drill stops when you release the trigger, allowing the center post to stop quickly. And all those 180mm weighted, heavy saws do NOT want to stop quickly. So no matter how tight I screwed the center section to the saw (aside from using a vice and cheat bar), it just popped out of the center post. And here you are holding the drill, the saw is still spinning terribly fast, and now it breaks loose and hits the workbench, flying across the room and crashing into some boxes. This could seriously hurt me or someone close by. This is a poor design and needs to be redesigned to have a locking mechanism for attaching the center post to the saw that cannot unscrew and cause breakage. dangerous flying rotating projectile of death. I can't believe QA testing was done to ensure the safety of this saw. I know product safety in China is ridiculous compared to safety in the US, but when I buy a tool I expect it to not cause damage or injury if used as intended. This item is sure to hurt someone as it is currently on sale. Do yourself and everyone else a favor and don't buy this. Buy something safe, not just cheap. If that review is hampered by a severed finger or other appendage, the writing time has been worth it. I was thinking of demonstrating it on video but I just won't risk it.