The mini scope herbst is one of our most popular types of herbst due to its durability from the AppleCore (registered TM) screw system. The photo above is showing the slimer profiled cousin the Hanks Telescoping herbst which offers a slimmer facial profile and is a good option when dealing with smaller patients. The parts are interchangeable and function in the same way and both offer a captive tube and rod system that helps prevent emergency calls due to separation. Each arm comes in 18, 21,24, and 26 mm. We select the size that offers the shortest profile and symmetry from left to right .