J&D Manufacturing 8 Stage Ventilation Controller8 Stage Ventilation Control This is an 8 stage control with two independent variable speed stages and 6 on off relays. Relays can be set to heating or cooling. It features a two line, 24 character LCD display screen and password security to prevent unauthorized setting changes. Display can be set to read as Fahrenheit or Celsius. Includes one 30 foot temperature probe. Optional lengths are available up to 500 and this control can take up to 4 sensor