Avoid dropping or spilling your API liquid tests with this Tube Rack that also doubles as a Drying Rack. 3D Printed from a clean and vibrant White PLA. The Rack helps to provide a clear contrasting background to help you read your tests more accurately. A slot in the back of the unit allows you to store you API test booklet. Simply flip the test tube upside down to dry. Vented barbs on the front allow your tub caps to dry. There are 3 ways to mount the kit. Use the Feet for free standing use. Use the wood screws for a permanent installation , or use the suction cups for temporary use on your aquarium glass.