The Fiber Optic Splice Closure is a wiring device used for overhead, pipe manhole, underground direct connection or protection joints of the field cable network. The box body of the product is made of high quality engineering plastic (PC), and the external fasteners and components are made of high quality stainless steel. The product uses 2 times of cable-clamp technology to ensure no additional loss of fiber in the box. The product has the function of breaking the electrical connection to and from the cable. The product has multiple multiplexing and capacity expansion functions. The valve is fitted with a valve to facilitate inflation and air pressure measurement during sealing inspection. A grounding lead-out device is also mounted on the housing. M-type fiber optic splice closure adopts a well-developed patented product - elastic joint sealing member, which is made of high-quality elastomer sealing material. It is scientifically formulated, injection molded with mold and numerical control equipment, and installed between the bottom of the fiber optic splice closure and the cover. It can automatically shrink and expand in the temperature change of -40 °C - +65 °C in the natural environment to ensure long-term sealing of the fiber optic splice closure. At the same time, it can reach multiple repeated opening, repeated use, and maintain good sealing performance, which solves the construction problem of expansion and maintenance of the fiber optic splice closure. The elastic joint sealing member is the first in China and the international leader. The whole set of fiber optic splice closure plastic parts adopts scientifically formulated high-strength PC engineering plastics. After injection molding by data control equipment, it can effectively stop the aging of materials caused by cold, heat, oxygen and ultraviolet rays in nature, and has excellent mechanical strength. The sturdy fiber optic splice closure shell and main structure can play the role of flame retardant, waterproof and shockproof, and at the same time protect the tensile, twisting and impact of the cable joint, and can be in the natural environment of -40 ° C - +65 ° C long-term use.