Aquarium Systems Instant Ocean Hydrometer

This hydrometer has an easy to read 2-color scale with a safe zone, improved no wet hands design, extra wide stabilizer base, accurate to +/- 0.001, full range scale from: 1.000 to 1.032 in 0.002 increments except in the safe zone, there it is in 0.0001 increments (specific gravity), 0 to 40 PPT in increments of 2 (salinity).
TYPE HAND HELD
AQUARIUM TYPE SALT WATER
Rinse hydrometer with fresh water before using. Slowly fill it by dipping bottom corner fill port below water surface until water flows up and over inner weir. Dislodge air bubbles by tapping hydrometer or pointer, gently with pencil. Placing hydrometer on a level surface, read specific gravity (inside scale) and salinity (outside scale). For most marine aquariums, recommended specific gravity is 1.020 to 1.024. Rinse hydrometer with fresh water before storing. Periodic cleaning is recommended to remove deposits that can accumulate on pointer, causing inaccurate readings. Soak hydrometer in mild acid (vinegar) for 30 minutes, then rinse.