My gauge is even simpler yet. It is a piece of aluminum with two notches at the bottom which sit on the rails and a square hole that the coupler has to pass through. It is very small and can even fit in your pocket.
Remember that the height gauge is made from metal (sturdy), and that it also has a projection to gauge the proper mounting height of the coupler, i.e. you can put the gauge on the track with a car and see where you need to cut or fill to get the coupler mounting pad the correct height. This is besides the obvious function of checking the height of an installed coupler.
To me it's a good deal, considering the total cost of my trains, couplers, etc.
I believe the #1 scale coupler is actually closer in scale size for 1:29, but after reading about how Kadees can ride over, and knowing the grades I would have and wanting to run very long trains, I resigned myself to live with the slight oversize in return for greater reliability.
So far, it seems to have been the right decision for me.