Different sizes...
Joe, I have the small and mid-size Loos Professional gauges from smaller boats but you will need the largest one for our H34's. The gauge documentation gives the tensil strength by wire size and what percentages of tension are applied per the gauge being positioned on a shroud. These B&R rigs are best set up off the boat to set up the pre-bend and upper shroud tensions, but can be adjusted when standing. Generally you would tension the shrouds to 12% to 15% of breaking strength, the higher if you are racing. The gauge has notches along one edge for the various size wire diameters that it measures, which correspond to a table on the gauge and in the documentation that comes with it. The instructions are very thorough and it is a first class product. Unfortunately the largest gauge is quite pricy, which has put me off getting one yet.