Ryuga Concave Professional Bonsai Cutter w/ Spring Assist The Concave Cutter is the single most important tool for Bonsai use and for which there is no substitute. Concave Branch Cutters, known in Japan as Mataeda Hasami are razor sharp tools designed for cutting branches flush to the trunk. Dimensions: 7/8 inch blades, 8 inches (203 mm) overall length. Comes with Spring assist for ease of use and a zippered carrying pouch. Carbon Steal