Acorn TempFlow
Acorn TZV-1 TempFlow 1/2 in. NPT Brass Thermostatic Zone Valve
A nice detail is how the zinc coated color complements stainless steel or aluminum parts nearby.
Acorn TZV-1 TempFlow 1/2 in. NPT Brass Thermostatic Zone Valve
You will find that the 1/4 in dimension is spot on for precision tasks.