Check the listing for details. Proof and Tralle Alcohol Hydrometer for Distilled Spirits. Condition: New. Listed at 9.95 USD. Normal 0 false false false EN-US JA X-NONE A Proof & Tralle Hydrometer is designed to test the alcohol volume in distilled spirits. The proof scale measures the U.S. International Revenue scale for Proof of Spirits. The Tralle scale will determine the direct percentage of alcohol in your spirits. To use the hydrometer, place a sample of liquid in a rest jar (available in are store). Gently lower the hydrometer into the liquid until it is floating. Spin the hydrometer to release air bubbles. At eye level, take a reading at the flat (not the meniscus) where the hydrometer emerges from the from the liquid. The Proof and Tralle Hydrometer will not take an accurate reading of liquids that contain high concentrations of sugar.Comes with hard case.