The metal pipes give superb appearance to your aquarium. Make an elegant curve line in your aquarium. Surface skimmer removes surface scum effectively. Made of harmless and sturdy 304 stainless steel, against rust and corrosion (Notes: Pipes should be cleaned before used in your aquarium tank). 16mm outer diameter fit for the canister filter tubing of 16/22mm. Easy to clean, remove convenient assembly. Package included: 1x stainless steel surface skimmer inflow, 1x stainless steel lily pipe outflow, 2 x acrylic fixture.