Standard 4mm inner diameter tubing is almost great for all your aquarium airline needs. Such as air pump, double head CO2 bubble counter, fine adjusting valve, bubble diffuser. Be made of PU material, non-toxic, cuttable and easy to clean, 3 meter and 5 meter optional. This tubing is safe for both fresh and salt water environments. Features: PU MATERIAL: Be made of PU material, transparent, non-toxic, cuttable and easy to clean. 4*6MM AIR TUBE: Inner diameter is 4mm, outer diameter is 6mm. 2 TYPES OPTIONAL: 3 meter and 5 meter optional, it is cuttable, meets all your needs. WIDELY APPLICATIONS: Suitable for air pump, double head CO2 bubble counter, fine adjusting valve, bubble diffuser, etc. Safe for fresh or salt water environments. WORRY FREE WARRANTY: Any problem, please contact our store without hesitation. Honor to serve you! Specification: Name: Air tube Color: Transparent Main material: PU Optional size: 3 meter: Length: 3 meter; Inner diameter 4mm and outer diameter 6mm 5