the inserting member holder 113 here the installed position of the sealing member 150 is not limited to only the inserting member holder 113 for instance as illustrated in fig5 the sealing member 150 can be formed to project from the blocking member 141 rather than the inserting member holder 113 also the sealing member 150 can be modified in other configurations according to other aspects of the present invention for example the sealing member 150 can be made of a first sealing member 251 and a second sealing members 252 formed at portions of the blocking member 141 and the inserting member 112 which are positioned opposite to each other respectively as illustrated in fig6 however it is understood that the first sealing member 251 may be provided on the inserting member 112 and the second sealing member 252 may be provided on the blocking member 141 in this case the first sealing members 251 may be formed of a triangle shaped groove and the second sealing member 252 may be formed of a triangle shaped protrusion which is inserted into the triangle shaped groove to prevent the blocking member 141 and the cap 111 from coming in surface contact with each other thus improving a sealing efficiency the triangle shaped groove of.