A passenger detection system is provided to determine if a passenger is present or not because the weight value corresponding to when the seat is empty has shifted. The compensation is performed through nonlinear filter operation in which a constant term is added to linear filter operation. The weight of said 1,3-propane sultone is between 0. Second locating members extending from the side walls of the body are arranged to adjoin a second surface of the board opposite the first surface when the connector body is mounted in the mounting slot. , wherein the knurl part comprises plural of knurls 6 having short width slits 6a and plural of knurls 7 having long width slits 7a, and knurls 7 is formed in the mixture with knurls 6.