A traditional style of airlock that is still preferred by wine makers or for longer term aging. The S-Shaped airlock is better for long term aging because the water in the airlock has less surface area and will not evaporate as quickly, It will also show positive pressure, which wine makers need to help indication that Malolactic fermentation is working. This S type air lock has a top cap with air vent holes and "max" mark on side. Drill a 12mm hole to fit the grommet. Height: 170mm (approx) *Usage: Fill to the line with boiled water or sanitiser and connect to your fermenter of choice.