Astro Pneumatic Tool 219 ONYX 3-Piece Die Grinder Kit with 90° Angle Die Grinder, Straight Die Grinder & 8-Piece Double Cut Carbide Rotary Burr Set - Perfect for Metalworking, Automotive Repair, and DIY Projects

Both units work pretty well and the included bits have held up great as well. I did buy a second set of bits to keep my aluminum and steel bits separate and I use these ones on steel and stainless and they've held up great. The grinders themselves work pretty well. As others have mentioned, sometimes they get a little hung up and won't spin but manually spinning them and then pulling the trigger seems to set them straight. I also had issues with the collet being difficult to loosen on the straight body tool and broke both the wrenches it came with. I made a set out of thicker 1/8" material and left a little more meat on the sides of the wrench and those have held up fine. Wish they just shipped with adequate wrenches in the first place. I'm also more careful to not overtighten that tool. I recently let my girlfriend use it for a stainless project she's working on and forgot to tell her about not overtightening and had a tricky time loosening it again. I'm still within the one year warranty and plan to send it back to Astro for service to see if they can replace the collet assembly for me. I suspect a burr left behind from manufacturing causes the issue for me. I called them to ask what they could do when I first had problems and 1) Got an English speaking human being within 30 seconds of calling who 2) Covered their warranty policy and estimated turn around time on repairs. I've bought other Astro tools and once had a punch set show up without writing on one of the punches in the set. A quick phone call later and Astro mailed me out a replacement with writing on the tool at no charge to me. They're California based so shipping for me is quick and affordable if I ever need to pay for it. Will be continuing to buy Astro as I build my tool collection up. They are built well enough for my needs and offered at relatively affordable pricing when compared to similar tools from more well-known companies.