Optical splice closures are used to distribute, splice, and store theoutdoor optical cables which enter and exit from the ends of the closure. There are two connection ways: direct connection and splittingconnection. They are applicable to situations such as overhead, man-well of pipeline, embedded situation etc. Comparing with terminal box,the closure requires much stricter requirement of seal. Sealing ring andair valve are required for closure, but that are not necessary for terminal box.