Another popular gauge is the Wixey WR300
http://wixey.com/anglegauge/index.html
I prefer the original Type 1 over the newer Type 2 (capacitive vs MEMS)
Bryan Hebert sells an adapter (3D printed I believe) that allows it to be mounted on the standard Robert incidence bars.
Thanks.....I have a couple of Wixey gauges and they work well.
i screwed a small piece of angle iron to the the bar and zeroed the iron to the bar on a surface plate.....but....I always worry that the Wixey will fall off the iron if I bump it and the magnet lets go.
I'll look at Bryan's site and see what he's got.