(THF310) This is a very helpful item that allows you to quickly take hydrometer readings from your fermenter with no siphoning or pouring. Just submerge the tube into your wine or beer and lift it back out. A one-way valve will automatically lock your sample in the tube. Now you can float your hydrometer inside the tube to take mess-free readings. When you`re done just depress the Fermentation Sampler`s special relief valve against the side of your fermenter to return the sample. No waste. It is 20 inches long. Works with all our hydrometers except the Precision Finish Hydrometer, Item #HY410. Hydrometer is not included.