Size: Standard inlet with outer diameter: 5mm adapt to 4-5mm air tube. (Please you can also find more measurement details in the photo). Special design makes it easily be hidden in your aquarium or other fish tank bubble decorations.

M01	Ball Shape Dia: 20mm(0.8inch)
M02	Ball Shape Dia: 25mm(1.0inch)
M03	Ball Shape Dia: 30mm(1.2inch)
M04	Ball Shape Dia: 40mm(1.6inch)
M05	Ball Shape Dia: 50mm(2.0inch)
M06	Round Disc Dia: 40mm(1.5inch)
M07	Round Disc Dia: 60mm(2.3inch)
M08	Round Disc Dia: 80mm(3.1inch)

Material: Made of high quality safe, washable material and plastic for long-time use, eco-friendly, odorless, 100% free from toxins.

Ultra-tiny air holes dissolve more oxygen into water and burst peacefully on the water surface. Widely applicable: Suitable for hydroponic systems, ponds, aquarium fish tanks, helping extend the life of your aquarium environment. Great accessories for your fish tank, air pump, air tube.

Tips: Please pay attention to the correct size before purchase! Soak the stone bar completely in water over 2 hours before use. For a better connection, before you use, please wet the connector and aquarium tube to get a easily install. Please ensure connectors have the hole all the way through.

Hi, dear. Any question please feel free to contact me firstly. I will try my best to help deal with your problems in a short time as soon as I receive your message.