Thermo-Est offers a wide range of threshold relays (two-wire technique powered by the 4/20 mA loop and four-wire technique with separate power supply) and indicators for mounting at the top of rods, DIN rails or for embedding in 96 x 48 format. The models are available in fixed-range analogue versions or in microprocessor controlled programmable versions with a HART or Profibus type communication protocol option.