This model works for alcohol testing ( to test the alcohol concentration in the alcohol solution, not the grape wines or the other fruit wines). Its unit is W/W (Weight/Weight), the refractometers working temperature is suggested at 20°C (about 18°C to 25°C). 
FULLY EQUIPPED with ATC, it automatically adjust itself to correct temperature discrepancies during use. Because refractive index is very temperature dependent, it is important to use a refractometer with automatic temperature compensation (ATC) to give you the most accurate measurement in any type of environment temperature. 

Features: 
Heavy-duty and lightweight with its aluminum construction 
High quality and accurate testing results are guaranteed 
Easy to focus & calibrate and very convenient to use 
Durable and built to last long 

Specifications: 
Measuring Range : V/V 0-80% 
Minimum Divisions : V/V 1% 
Accuracy : ±1% 
Length : 202mm 
Weight: 164g 
Heavy duty (Durable Aluminum) 

Set Includes: 
1 x Portable Alcohol Refractometer 0-80% W/ ATC 
1 x Pipette 
1 x Mini Screw Driver 
1 x Soft protective carrying case