To easily perform the mounting operation by installing a pair of fitting parts fittable to a mounting eye, on a mounting face, and forming a thin part between the pair of fitting parts, at the mounting face.

A pair of fitting parts 22 fittable to a mounting eye 40, are projected from both sides of a mounting face 20. The mounting face 20 comprises a thin part 24 between the pair of fitting parts 22. On this occasion, the thin part 24 is formed by notching a packing body 1 along a longitudinal direction, to an internal cavity 3. The packing body 1 can be easily mounted on the mounting eye 40 by successively fitting a part of the packing body 1, where a point 23 of the fitting part 22 is kept into contact with an upper edge of the both side edges of the mounting eye 40, in a condition that the fitting part 22 is fitted to the mounting eye 40 at one edge of the packing body 1. The packing body can be easily fitted after a part of the packing body 1 is inserted, because the sections perpendicular to each other in a longitudinal direction, have the same shape, and the outer diameters of the fitting parts 22 are same as each other.