For Laboratories routinely testing for microbes requiring a CO2 rich, reduced O2 atmosphere, the Anaerobic box-L provides a convenient solution. The Anaerobic box-L is lightweight yet robust. The uncomplicated design makes it easy to maintain and load with a compartment for both the gas kit and also indicator, minimizing the possibility of malfunction. The shape of the Anaerobic box-L also makes it easy to store and will save space in the incubator over more conventional round jars with bulky lids that include valves and gauges.