3 very well preserved original copies, wood/paper, each signed, each with a functional compass, rarely in this beautiful condition. A detailed description and operating instructions can be found here: Source (https://www.cortrie.de/go/rAV). ==References====External links== ==References====External links== Paul Philipp Beringer (1760-1834) and his older brother David Beringer (1856-1821) were in the second half of the 18th century. ==References====External links==* Official website Apparently, the Beringer sundials were very successful. This can be seen from the large number of preserved pieces. Many museums still own such folding sundials by David Beringer.