A collar assembly for coupling a blade assembly and a removable jar to the base of a motorized blender includes an interlock assembly that prevents coupling of the blade assembly to the blender motor unless the jar is secured to the collar assembly, and prevents removal of the jar from the collar assembly when the collar and blade assembly is coupled to the blender base. The method enables to prevent an improper modification or an erroneous modification even when the point group includes a point having a low reliability, thus to achieve proper modification. The dovetail channels provide anchorage points for cross members within the panels as well as weather-stripping and mechanical joints between panels and a building frame. An audio amplifier tunable to a listening room removes very low narrow frequency band components of an audio signal. Next, policy and configuration information is downloaded to the network device using that secure communication link. Advantageously, the caller can control which Agent or which sub-group of Agents should respond to hisher call, taking into account the different waiting times associated with a particular Agent or the first available Agent when the caller reaches the top of the queue.