Door slab replacements are a big part of my business.  I have used the original version of this tool for many years.  Admittedly it was somewhat difficult to set up which is why I only used it when I had multiple slabs to install, like door upgrades in condo's or townhouses.  It served me well, however it had become loose and some of the components were worn to a point where I constantly had to check and/or readjust it. Also, parts just weren't available anymore.  This prompted me to purchase PC's updated version.  I can't tell you enough how sweet this tool is compared to what I went through to use the old one.  It takes less than 10 minutes to set up and in the way it's designed it holds all of the adjustments well.  It adapts quickly if I'm retrofitting multiple slabs with different hinge spacing and positions. Using it to relocate hinge mortises on the jambs or taking existing locations and spacing then transferring the locations to a slab or visa versa is the best part.  I had the benefit of working with the old tool first so I had an understanding of the concept and process and what the final result should be.  This why I say that once you've used this tool for a little while and get the "feel" of it, especially if this is your first time with a gauge such as this, you can't help but be pleased. I recommend purchasing part #86018 (3 1/2") jamb gauges from Porter Cable Servicenet.  I bought the one size, since it's the most common hinge, but I use it for all of the other sizes. If you end up buying the 59381 you'll understand why when you read about the jamb gauge's function in the instruction manual.  I hope this helps.  Lots of luck.