I purchased these levels from Amazon.com. The main problem was the longer level had a 3/16" crown in the center of it! I called Irwin and their technician said to return to Amazon and have them send me another one. Well I sent it back and ordered STABILA's set which is perfect. Also the levels vials are adjustable which STABILA's are not. I'd prefer not to have to adjust vials when I need to be hanging doors. I've used other Irwin products and like them that's why I tried their levels, even though all my past levels have been STABILA. Stick with STABILA!!!!