CONTROL WIZARD CO2 SYRINGE TESTER. Allows accurate testing of co2 levels. Includes 2 tubes. More tubes may be purchased. See CO 116.Draw 100 cc's of you growing area's air into the syringe. Break off both ends of a glass reagent tube and insert the tube into the syringe with the arrow on the tube pointing away from the syringe. Now gently push all the captured air through the tube. Now examine the tube. Where the purple color stops and the white begins is a PPM number. That's the co2 count in your area. Yep, it's that simple.