Flareless tube fittings are used to attach two sections of pipe together and commonly have ferrules in them. Flareless tube fittings do not require that the metal tube is flared before installation. The ferrule compresses onto the tubing which creates a seal that is able to withstand very high pressures. Tube fittings are typically used to water taps and toilet stop valves, as they are well suited to the confined spaces where these types of valves are commonly found.
Flareless tube fittings are typically composed of two parts: an inner compression ring (ferrule) and an outer compression nut. After installation, the nut is tightened and the ferrule is compressed between the nut and the receiving fitting. The ferrule seals the space between the tube, nut, and receiving fitting, forming a tight seal that is able to withstand high pressures.