Sturdy, nicely made tool, very easy to use:  Match the arms to the corner, read the scale, set the saw, cut the trim.  However, on the first one I received the scales did not match.  For example, on a (maybe) square corner the single cut scale would read 0 and the miter scale would read 46. Same thing on inside or outside corners whatever the angle.  So which scale is correct?  Only way to find out is to cut and then recut the board.  The purpose of this tool is to find and measure SMALL inaccuracies.  If you can't trust the scales then it is simply an expensive angle take off tool and actualy less useful than a regular T bevel.  I returned it to Amazon and very quickly received a replacement - which was no different.  Not ready to give up I called Starrett and spoke with a very helpful and knowledgeable guy named John in tech support.  He indicatd that the company is aware of the problem and is working to fix it.  He suggested I return the tool to them and they would hand pick an accurate replacement.  I sent it to them yesterday.  Starrett has a well deserved reputation for making very high quality products and that is the main reason I bought this one.  My current low rating is provisional depending on how things turn out with the replacement.  I'll have an update (hopefully good) soon.

Update:  I received the hand picked replacement from Starrett - and the scales line up fine.  This 505 is a sturdy, easy to use and very helpfull tool.  5 stars.
Sturdy, nicely made tool, very easy to use:  Match the arms to the corner, read the scale, set the saw, cut the trim. However, on the first one I received the scales did not match. For example, on a (maybe) square corner the single cut scale would read 0 and the miter scale would read 46. Same thing on inside or outside corners whatever the angle. So which scale is correct? Only way to find out is to cut and then recut the board. The purpose of this tool is to find and measure SMALL inaccuracies. If you can't trust the scales then it is simply an expensive angle take off tool and actualy less useful than a regular T bevel. I returned it to Amazon and very quickly received a replacement - which was no different. Not ready to give up I called Starrett and spoke with a very helpful and knowledgeable guy named John in tech support. He indicatd that the company is aware of the problem and is working to fix it. He suggested I return the tool to them and they would hand pick an accurate replacement. I sent it to them yesterday. Starrett has a well deserved reputation for making very high quality products and that is the main reason I bought this one. My current low rating is provisional depending on how things turn out with the replacement. I'll have an update (hopefully good) soon. Update:  I received the hand picked replacement from Starrett - and the scales line up fine. This 505 is a sturdy, easy to use and very helpfull tool. 5 stars.