The ROXY-4 universal controller is a versatile, four channel, O2 and general purpose gas controller. It can regulate many variables such as oxygen, CO2, water vapor, or pressure by using the analog output of an external analyzer or fuel cell. Four independent channels give the flexibility to control four separate chambers or multiple variables in fewer chambers. The set point control algorithm can create stable or profiled environments for cell cultures, material testing, hypoxia, hyperoxia, and many other applications.