Features: 1. Product Structure Analysis: Fast measurement, accurate data, convenient use, wide application and complete equipment. 2. Adjustable Eyepiece: When salinity refractometer scale is not clear, you can gently rotate the eyepiece for adjustment. 3. Clear Reading: 0‑28% salinity refractometer has fast detection, accurate measurement, clear display and convenient use. 4. Cover Plate Function: The use of cover plate is to protect the prism and make the measurement more stable. 5. Calibration Screw: Drop distilled water on the prism and turn the zero adjustment screw to adjust the dividing line to 0% of the scale. Specification: Item Type: Refractometer Material: Plastic, Aluminum Color: As Pictures Shown Weight: Approx. 253g / 8.9oz Salinity: 0-28% Product Size: Approx. 17.2x4x4cm / 6.8x1.6x1.6in Package List: 1 x Refractometer 1 x Straw 1 x Lens Cloth 1 x Screwdriver 1 x Manual 1 x Plastic Box Features Fast and Accurate Measurements: Get precise and reliable results with this 0-28% Salinity Optical Refractometer. It provides fast detection and accurate measurement, ensuring you have the most up-to-date information for your aquarium or seawater. Adjustable Eyepiece for Clear Readings: Easily adjust the eyepiece to ensure a clear and sharp scale reading on the salinity refractometer. No more struggling to interpret the results, making it convenient and user-friendly. Enhanced Stability with Cover Plate Function: The included cover plate protects the prism, ensuring stable and consistent measurements. Enjoy peace of mind knowing that your readings are reliable and consistent. Easy Calibration for Optimal Accuracy: With the calibration screw, you can easily adjust the refractometer to ensure accurate readings. Simply drop distilled water on the prism and adjust the dividing line to 0% for precise measurements every time. Versatile and Complete Equipment: This portable and handheld refractometer is suitable for a wide range of applications. Whether you're a hobbyist or a professional, this refractometer is an essential tool for anyone working with aquariums or seawater.