Flight saving triangle - Flugsparrendreieck
The flight rafter triangle , rafter triangle or colloquially also Züri-Vieri is a support structure for canopies that has its historical origin in the Zurich region . Flusparrendreiecke prevent slipping flight rafters by steep rafter roofs. They are arranged with wall and intermediate purlins or only with wall purlins. 
The wooden construction was used from the 17th century and is still used with success today  . The mostly elaborately decorated rafter triangles, which are visually reminiscent of the number 4, are an example of carpentry.  Flying triangles were also used as decorative elements on purlin roofs, although they have no static function there. 
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