From the product description, check product page for current description, price and availability:

This oversized 3-piece airlock can hold 50% more water or sanitizer so your airlock is less likely to evaporate dry or get sucked dry. When the temperature drops, your fermenter will suck in solution from the airlock, and if the temperature drop is significant the airlock can be completely emptied. An empty airlock opens the door for airborne spoilants to make their way into your fermenter unchecked. The extra large 3-piece airlock offers your fermenter even more protection, and is especially useful when cold crashing.

While a simple device not all airlocks are the same. Some other designs have only a couple holes in the plastic lid and this can cause the airlock to pop out during an active fermentation. Just like our normally sized airlock, our design features many holes in the lid that allow CO2 to escape easily. Additionally some other airlocks have a cross hatch design on the bottom while our is open to allow Krausen foam to enter the airlock if necesary. Better to clean your airlock out than to find it laying on the floor next to your fermenter 3 days later.

Another cool feature of this 3-piece airlock is that 1/2″ ID tubing will fit onto the center post for use as a blowoff. This can be handy if you have a really active ferment that is blowing out the top of your fermenter.

Please Note: Airlock only – stopper not included.

From the product description, check product page for current description, price and availability:

This oversized 3-piece airlock can hold 50% more water or sanitizer so your airlock is less likely to evaporate dry or get sucked dry. When the temperature drops, your fermenter will suck in solution from the airlock, and if the temperature drop is significant the airlock can be completely emptied. An empty airlock opens the door for airborne spoilants to make their way into your fermenter unchecked. The extra large 3-piece airlock offers your fermenter even more protection, and is especially useful when cold crashing.

While a simple device not all airlocks are the same. Some other designs have only a couple holes in the plastic lid and this can cause the airlock to pop out during an active fermentation. Just like our normally sized airlock, our design features many holes in the lid that allow CO2 to escape easily. Additionally some other airlocks have a cross hatch design on the bottom while our is open to allow Krausen foam to enter the airlock if necesary. Better to clean your airlock out than to find it laying on the floor next to your fermenter 3 days later.

Another cool feature of this 3-piece airlock is that 1/2″ ID tubing will fit onto the center post for use as a blowoff. This can be handy if you have a really active ferment that is blowing out the top of your fermenter.

Please Note: Airlock only – stopper not included.