lower urging member an o ring 150 b made of rubber is put on the groove 150 a the groove 150 a and the o ring 150 b consist of a sealing unit 150 the attaching section 12 has its lower staged portion matingly seated on the other two shoulders of the interconnecting section 10 with the reduced bore member 121 being sealingly engaged with the o ring 150 b see fig4 that is the bore of the reduced bore member 121 is blocked for stopping any fluid flow a rubber o ring 16 is put on an annular groove not numbered on an outer surface of the interconnecting section 10 to secure the interconnecting section 10 onto the lower portion of the attaching section 12 a ring shaped flexible member 13 comprises two opposite upright latches 130 having a ridged end 131 the ring portion of the flexible member 13 is rotatably fastened between the flange 120 and the top annular flange not numbered of the interconnecting section 10 when the flexible member 13 is mounted the female sub assembly 2 comprises a tube connecting section 21 adapted to couple to the other tube 3 a separate attaching section 22 and a gradually enlarged interconnecting section 20 integrally formed with the tube connecting section 21 to.