Unbreakable, watertight, airtight, dustproof, chemical resistant and corrosion proof Buoyancy allows case to float in salt water with 3.6 kg (7.94 lb) load Includes an automatic purge valve for quick equalization after changes in atmospheric pressure Features an exclusive 6.4 mm (0.25 in) neoprene O-ring and ABS latches for excellent seal For use with the following test tools: Multimeters: 287, 289 Earth Ground Testers: 1621