This allows you to shut off, disconnect and reconnect water-carrying hoses at the aquarium in just 5 seconds. And then you can disconnect your filters, UV-C water clarifiers and any other technical equipment from the aquarium before cleaning etc. It couldn't be simpler or more convenient!
You can find out more about this handy extension here: JBL double stopcock+quick coupling
Further useful accessories and tips to make your hobby easier can be found in the Themeworld Aquarium at: Useful equipment