. . "Namely, the mesh-like member 30 is made of polymeric material such as polytetrafluoroethylene or the like, and comprises a plurality of vertical members 32 connected to each of intersection portions of first and second horizontal members 31, 31 forming meshes of the mesh-like member 30 so that the respective vertical members 32 intersect a face defined by the first and second horizontal members 31" . . .