To surely seal a mouth of a main body case with a mouth cover, and to detach the mouth cover integrally with a lid member when detaching the lid member.

On a front face 34d of a mouth cover 34, a locked cylinder part 42 is provided which has an insertion hole 42d opened in upper and lower end portions and is formed cylindrical. On a rear face 33b of an escutcheon cover 33, an arm part 35 is provided of which one end is continued to the escutcheon cover 33 and the portion from the one end to a distal end rises upwards separately from the rear face 33b, and which is inserted from a lower side into the insertion hole 42d of the locked cylindrical part 42 and formed separate from a front side portion in an inner surface of the insertion hole 42d while being inserted.