The BART tester requires no microscope, no laboratory, no incubator! The test is done at room temperature in your office or treatment room, on a desk, shelf, or in a cupboard and is viewed daily. Different microorganisms like to grow at various heights in a column of water to which nutrients have been added. BART testers contain nutrients in the base of the column and a ball. The ball restricts the amount of oxygen entering the water column so that aerobic organisms grow around the ball and anerobic organisms grow deep down in the water column. By changing the nutrients in the base of the column different organisms can be encouraged to grow. BART determines presence and activity levels.Full instructions for the use of BART biodetectors are included with your purchase. Click here for the general User ManualEach individual test consists of: Test vial with media and BART ball & one extra cap. One color chart is included in each box of 21 testers.There are two versions of BART Testers; Field and Lab. We carry Both. The Lab BARTs are designed for laboratories and have only the inner tube that contains the media and ball. Lab BARTs are individually packaged in aluminum foil pouches and have a 4 year shelf.