A Speaker Side Air Supply Cabinet that has three things that are working together the Speaker Side Air Supply ducts, the Front Air Chamber, and the Bass Horn. In operation, when the water flows through the impeller, the impeller is rotated, and the magnetic member is moved to pass by the detector intermittently so that the detector can transmit a detected signal to the circuit board which can calculate the rotation speed of the magnetic member so as to obtain the water flow rate. This invention further relates to use of the supported nonmetallocene catalyst in olefin homopolymerizationcopolymerization, which is characterized by a lowered assumption of the co-catalyst as compared with the prior art. The support element has an optimized shape to prevent the core from fracturing during the casting process and to minimize operating stress in the metal part around the area formed by the support element. More fans can be added in series or parallel as needed to provide adequate airflow. A decentralizing function for the objective and stop relative to the detector or the reticle is arranged to prevent beams reflected byte surface or surfaces of the detector or reticle from passing back through the stop aperture.