High quality pyknometer: The pyknometer has a 0-200 proof and 0-100 tralle, marked in sharp and easy to read font. It can help you accurately calculate and monitor fermentation progress. Easy operation: Place the tester vertically into the wine at a standard temperature (usually 20 degrees Celsius). When the wine stabilizes, the reading above it remains level with the liquid surface, indicating the alcohol content. Value Pack: which are perfect for brewing beer, wine, cider, mead, kombucha, and distillates. The perfect family or brewing enthusiasts. Scope of use: High alcohol content is more accurate at high alcohol content, but may not be accurate at low alcohol content. It is also not suitable for measuring sugar or other components in wine. Temperature effect: Distillation supply can accurately read, but temperature can affect the accuracy of reading. You need to first understand the temperature of the surrounding air and liquid, and then consult the "Adjustment Chart" (Internet search) to determine it. Material: Glass colour: As Shown Package Contents: 4 x hydrometers Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.