The Maxtec MAX-23 Replacement Oxygen Sensor is compatible with the following:

City Technologies [MOX-1]
Criticare [Poet IQ 8500, IQ2 8500Q, CAT644 Sensor]
EnviteC [OOM-102]
Maxtec [R116P06]
Teledyne [R22 MED, #C-44611]
Viasys (Bird / Carefusion) [Infant Nasal SiPAP]