Color: Black Size: about 52*4mm Insert the vent tube between the air pump and the aquarium water to prevent the water from backing up into the air from the air tube . An essential accessory for every air pump and a good protection in case of power failure or breakdown. Includes: 6 Air Pump Check Valves Note: As the size above is measured by hand, the size of the item you received may be slightly different from the size above. Meanwhile, please be reminded that due lighting effects, monitor’s brightness/contrast settings etc, there could be some slight differences in the color tone of the pictures and the actual item. Your understanding will be highly appreciated. Package Included