A Tibia Clausa is a type of pipe organ pipe. It is a large-scale, stopped wood flute pipe, usually with a leathered lip. The rank was invented by Robert Hope-Jones. Tibia Clausas provides the basic foundation tone of the organ with few overtones or harmonics. The Tibia Clausa is arguably the most important rank of pipes in a theatre pipe organ, with some organs having as many as 5. The stop shares similarities with the Bourdon and the Gedackt found in some church pipe organs. In the 18th and 19th centuries, Tibia Clausa was sometimes used as an alternate name for . Most tibias are made from wood, as by Wurlitzer etc., although examples of metal tibias may be found made by the John Compton Organ Company.