Features: 1.The salinity tester needs testing sample le than a traditional hydrometer, just 2 to 3 drops and wait for few seconds, you will get accurate readings. 2.Saltwater refractometer Specific Gravity (D 20/20) and parts per thousand and replaces your poor quality and difficult to read hydrometer. 3.Salt meter with dual scale: 0~100(1=1PPT=1000ppm, PPT means"parts per thousand", specific gravity range 1.000 to 1.070 4.Automatic compensation temperature (ATC) function makes the refractometer more accuracy, shifts in ambient temperature within 50-86 wont effect the readings. 5.Easy to calibrate and easy to operate, optic salt refractometer no batteries required, more cheap than a digital refractometer. 6.Handheld salt water tester is made of non-staining, non-corrosive aluminum and ABS plastic, lightweight and easy to carry, durable to use for long time. Product Description Name:Salinity Refractometer Material:Aluminium Alloy Measurement Range:0-100ppt Battery:no need battery Size:16X5.9X4.9 cm Package include 1 x Refractometer 1 x Plastic pipette 1 x Mini Screw Driver 1 x Cleaning Cloth(Random color) 1 x Plastic Box How to use 1.Calibration: just 2-3 drops of distilled water or fresh water, using mini screwdriver to calibrate. Through the eyepiece to check the blue line is on zero. 2. After calibration, place a 2-3 drops of test sample onto the Clean main prism 3. Close the daylight plate and hold it under a light source, then check the reading. 4. After used, use the cleaning cloth to wipe the prism and storage. Warm Tip 1. Please clean the test surface after use 2. Gla instruments, please keep them well and do not drop them. 3. Please do not let children touch to avoid injury.