Oerlikon Leybold PENNING Gauge Transmitter PTR 90 Sensors are designed for vacuum measurement in the pressure range of 750 to 1x10-9 Torr (1000 to 5×10-9 mbar). The PENNING Transmitter PTR 90 Sensor Gauge can be operated in connection with an Oerlikon Leybold Vacuum gauge controller CENTER ONE, CENTER TWO, CENTER THREE or with another controller.