I just installed Wixey's new Table Saw Fence Gauge on my saw last week, and I'm truely impressed. I can now easily position the rip fence accurately and repeat those positions any time that I want to. One of the things that I really like is that I can remove and replace the saw fence without loosing calibration. The gauge stays on it's track and re-connects to the fence via a rare earth magnet. Calibration/re-calibration is easy though, just position the fence against the saw blade and zero the display. The installation took me less than 3 hours and was relatively easy to do, but you have to work slowly and take care to position and mount the encoder strip to your fence rail accurately (square, parallel, and stable) . It displays in inches or millimeters, in absolute or incremental mode, by simply selecting the display mode via push buttons, and it doesn't even loose it's calibration if it is turned off and the fence gets moved. The position counting/encoding portion of it stays active even when the display is powered off, so it is always ready to just turn on and use.
I had been considering a Saw Train by JoinTech to get better fence accuracy, but I think I just saved a bunch of money by buying this instead. My first cut was on a piece of 3/4 cabinet birch ply. After calibration, I set the fence to 2.000" and made the cut. When I measured the piece it was 2.003". WOW !!
I have no connection to Wixey. I'm just very satisfied with their products. I now own their angle gauge and their saw fence gauge. Their planner gauge is now definitely on my wish list.