The Living Sea Hydrometer is important to maintain proper living conditions for your fish, The use of the hydrometer is important to check specific gravity of aquarium water and to ensure all replacement water has the same salinity as your aquarium, The Living Sea Hydrometer is a great tool for maintaining your aquarium environment, The Living Sea Hydrometer Features and Benefits:, - Easy placement, - Made of durable glass, - Easy to read, - Ensures proper gravity of aquarium water, 8"" height SKU: RCHG0805