Bridge thermostats are variable heating thermostats for use with different bath sizes, with a stronger pump and a higher heater power than immersion thermostats. LAUDA bridge thermostats are available in two versions with different pump performances and immersion depths. PB models have a pressure/suction pump and require a bath depth of 200 mm, whilst the PBD models have a more powerful pressure pump (D) and thermostat baths of a depth from 320 mm. In addition, both series of models differ from one-another through the selected control head: Master or Command (C). Through variably extendable telescopic rods, all models can be attached without problem to baths with a width of 310 mm up to 550 mm.