Yokogawa's Zirconia oxygen detector systems offer a variety of calibration units for quick, easy control of calibration gases giving the user simple, accurate calibration. Users with single-point measuring systems, such as the model ZR402 converter, may choose either manual or automatic calibration units, models MC1 or AC1, respectively. For users with multi-point measuring systems, such as the model AV550 converter, the user has a choice of either a 4- or 8-channel auto calibration unit, models AC4 or AC8, respectively.