These Leybold IONIVAC ITR 90 gauges are a combination of Pirani and Bayard-Alpert (hot cathode ionization) sensors. They come with KF-25 vacuum flange fittings and have a single filament. They measure vacuum pressure from 750 to 3.8x10-10 Torr (1000 to 5×10-10 mbar). The Leybold IONIVAC ITR 90 is designed for vacuum measurement of non-flammable gases and has an output pressure signal that is logarithmic. These Leybold IONIVAC ITR-90 gauges can be operated in connection with the TURBOLAB 80 or with another evaluation unit. These items have Leybold part number 12 091. The manual and brochure is available for download below.