Not usable. I've tightened everything, but when using a mini cut-off wheel it starts to creep. It's terrible! Parts must not be pushed out by themselves. I tried to lock it but it won't lock. I think my instrument is broken. The manual is also terrible because it doesn't say how to make sure it's installed properly. It's not exactly easy to assemble and often requires more tools than just "plug in and tighten". It looks like the kit itself is great. I like all types of attachments and how to use them. But since I can't use it, I can't give it a high rating.