Vernier sells Grommets for CO2 Gas Sensor (CO2-GROM) that can be used to insert a CO2 Gas Sensor (CO2-BTA), O2 Gas Sensor (O2-BTA), Go Direct® CO2 Gas Sensor (GDX-CO2) or Go Direct® O2 Gas Sensor (GDX-O2) into your own container, or to add more sensors to a BioChamber 2000 (BC-2000) or BioChamber 250 (BC-250). You will need to drill or cut a hole that is 1.5 inches in diameter. The groove in the grommet will accommodate materials up to 1/16 inch thick.