How to use your GVDA GD316 GD317 Digital Brix Refractometer Sweetness Tester Meter Watermelon Sugar Content Measuring Cutting Fluid Fruit Juice Concentration
1. Cleaning: Cleaning the optic with cleaning cloth (Use alcohol or soapy water clean it if there oil liquid or not easy to clean)
2. Drop samples
3. Close the lid
4. Press 
