These connectors are perfect for tapering 16mm tubing down to 6mm tubing, when using large systems. They are inserted into the line at the point where an AQUAvalve or aquaPot is placed. They provide a tight connection unlike many other types of reduction fittings. They work exactly the same way as the 16mm to 6mm cross connector but this installation has one connection for 6mm tubing while the cross connector offers two connections for 6mm tubing.