A filter circuit having two pass bands includes first and second bandpass filters which are connected in parallel with each other. This results in a toughening mechanism caused by compressive residual stress around the microspheres which significantly increases the specific fracture energy of the epoxy resin. A second signal is received from the second positioning system. The hypersulfated disaccharides are made from carbohydrate starting materials. The front end edge portion 4 is formed by inwardly pressing and deforming the front end portion of the pipe body 2.