The thinning device FLEXITREE, which became known as the “Bonner System” for fruit set regulation, is produced by CLEMENS and sold worldwide. The patented development of Dr. Damerow and Dr. Blanke serves to mechanically knock off the blossoms of fruit trees in spring with a rotating shaft, thus avoiding the use of hormones. The device is flexibly configurable and can be perfectly adapted to the crown structure and different tree heights by means of various adjustment options.