Straight Coupling. Joint clamp for tubes of the same diameter. Do not use for heavy vertical loads. Alternative clamp is Type 9 used as an internal spigot.
Another big plus of the black coating is, that the color gets into the material really deeply, which prevents the connectors from corroding. The paintwork is not resistant to UV radiation and is therefore not suitable for outdoor use. The tube fittings are equipped with black-colored stainless steel adjusting screws with cutting edge.