The CO2 varroa tester is a humane way of counting varroa from a sample of 200 bees. The Bees and Varroa are anesthetised, allowing the varroa to drop off the bees and be counted. Bees can then be returned to the hive. Kit comes with measuring container, CO2 dispenser and two 16g bottles of CO2. (enough to carry out up to 4 tests). Full instructions are supplied.