Product DescriptionThe Three Place Flip-Top Hydrometer case is designed to conveniently carry three 15-inch API thermohydrometers. The black case features a rugged plastic outer shell with separate interior compartments, each lined with felt. The felt-lined lid is cut at a 30¬∫ angel to allow it to arc from the hydrometers when opening and closing, preventing stem breakage. Two models are available. The 403B088 model uses a spring-loaded hinge to hold the lid in the open or closed position; the 403B089 model uses a positive tension latch that holds the lid closed until released.