The Barnes & Jones thermostatic radiator steam trap, model 122S, features a 1/2" trap connection in a straight pattern. Thermostatic traps are ideal for low pressure heating systems. The thermostatic element expands when steam is present, closing the trap, and contracts when cooler air or condensate is present, opening the trap, which allows the condensate to drain. The 122S is cast bronze and has a 25 psi maximum operating pressure.