airlock can be used for wine making, beer , fermenting sauerkraut, that can satisfy your daily fermentation need. Simple to press the stopper onto the carboy, insert the beer airlock to the stopper, pour some water into airlock and cover the lid to complete all operations. airlock makes easier for the fermentation caused it could effectively isolate the air to prevent oxidation and allow the whole fermentation process to be automatic fermentation and exhaust at normal temperature without manual control. Note: use, please boil and disinfect the airlock with boiling water. Wash with water after use. size: Drain valve length 17cm The stopper has holes 2.1x1.5x2.4cm Material:Plastic + silicone colour:white Package Contents: 6 * exhaust valve 6 * No. 3 stopper Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.