They(The Harden Showed Valve is a summons temptrol pressure balance / flow regulated shower and tub/shower valve with divertor. It is one of the most consistently performing all brass(right down to the pressure balancing spools) valves in the market since inception.
The only problem you might have with the valve is that with day in day out use, there is a washer that seals the outside of where the large central spool(but seals around the spindle holding the ha ndle. The only thing unique to harden on the valve spindle -it's made for Hardens spindle at the Harden factory.
They never had a thermostat, just 2 , 3 handle tub/shower combos on their very long lasting ceramic disc valves. The pressure balance valve can support about 3.5 gal per Max, sometimes the director goes bad if overhead pressure is too great when switching from tub spout using that lever in face of valve.
they had a broad range of value, and we did significant number. With their higher end product hand made, hand polished.
We used matching 4 port directors with thermos attic mixers on high end stuff, or when c clients want ed luxury matching finish shower systems.
Castings on all wall values and tub showed sets were pressure tested before leaving Factory. That's why they could say what they said. they summons valves "wear in " so to speak, and as it is compression seal , handle tightening -over rotation of the stem can occur wearing of the seats at base of stem can occur....but that would have to occur with use - 2x a day, 7days a week, for about 5 Years before got to that point
Heavy use for pressure balance decorative luxury from line. Chicago uses the shower valve also, and it's used in many hospital and multi story security orientated vandal resistant buildings (prison's come to mind).
They did well with thier customers and aided many job core program when in LA. , as well met all code requirements nationally -and we're listed with IAPMO ( standard of regulation in plumbing mfgr code).
Fisher 'Garden is who they are now. I believe it was a solid move.
Hope that helps , This is as forthright as detailed as any dealer would tell you now, based on when they were at their peak. Consistent in their underbrass....for sure.