Specifications: Item Type: Sea Hydrometer Product Material: Plastic Product Size: Main Body: Longest Part: Approx. 11.2cm / 4.4in Widest Part: Approx. 3.8cm / 1.5in Highest Part: Approx. 15.3cm / 6in Suitable Type: Suitable for brackish water and marine fish tanks. Product Function: Dedicated test concentration Application Method: 1. Insert the hydrometer below 15 cm to prevent pollutants such as oil film from affecting the accuracy of the test. 2. When the water is full (level with the top of the baffle), take out the hydrometer and place it on a level surface. 3. Air bubbles attached to the pointer will cause inaccurate readings. Carefully tap the hydrometer to shake out the attached air bubbles. 4. Get the reading of the hydrometer, the reading of the oceanarium should be between 1.021 and 1.023. The reading in the rock aquarium should be between 1.024 and 1.026. 5. Use hydrometer in water with a temperature range of 68-86F (20~30℃). 6. Clean the hydrometer after each use. The remaining salt crystals in the hydrometer will affect its accuracy. Soak the hydrometer in warm water for 30 minutes, then rinse with water to remove salt crystals. Voltage Parameter How to Use Package List 1 x Hydrometer