If you keep your carboy in a fermentation locker or other area with little to no head space, every inch counts. We love these low-profile 2-piece airlocks for their compact size and simple design. Instead of a floating plastic "hat", the center piece is molded into the lid. One less thing to clean and misplace! This is the very smallest airlock we sell and works well with fermentations up to 7 gtallons. 

• Holds approximately 0.4 fl oz (12 ml)
• Chamber - 1-1/2" tall x 1-3/8" diameter
• Stem - 1" long
• Stopper not included