Thermco GW2510 Plain Form Talle And Proof Scale Alcohol Hydrometer, 0 to 100% Tralle Range, 0 to 200% Proof Range, 300mm Length Tralle Scale Measures the Percent of Alcohol by Weight in Water Proof Scale measures the Percent Alcohol by Volume Multiplied by Two Internal Revenue Specification Proof Scales Suitable for Certification 1% Tralle Scale Division and 2% Proof Scale Division