The apparatus for deployment of a therapeutic device such as a micro-coil detachably mounts the therapeutic device to a distal portion of a pusher member. The null response is utilized to determine presence of terrain. Since the body is wider on the diaphragm side, the wave generator 7 can be easily fitted into the flexible external gear from the diaphragm side. A next step includes providing feedback information about the detecting step from the first layer protocol to a higher layer protocol. The first track defines a drop aperture adjacent the rear end thereof enabling the passage of product from the first track onto the second track, whereby successive forcible loading of product onto the front of the first track causes the product to pass, under the influence of gravity, to the second track for display and dispensing.