The unique sealed mode has obtained the national patent and its highly strength, rot resistance and anti-oxide have been tested by state organization. Applications: 1) Used for the protective connection between two or more optical cables 2) Suitable for single core fiber optic cable and ribbon fiber optic cable 3) Suitable for such laying modes in fiber optical cable circuit as aerial, pipelined and direct-buried installation Environment condition: 1) Environmental temperature: -40°C ~ +65°C 2) Atmospheric pressure: 70 ~ 106KPa Main technical indexes: 1) Airproof performance: airing pressure inside box 100KPa, pointer immovability after 24 hours or no air bell within 15min when parked in the common temperature water 2) Re-encapsulation performance: no change in the index of air-proof performance after three times of repeat encapsulation 3) Insulation resistance: ≥2 x 10,000mΩ 4) Voltage-resistance strength: under the effect of 15kV DC/1min, non-puncture, no arc-over