Features: Adopting a revolving buckled airtight mode of connection, this product is ensured of stable and firm core contact without exposure to the outside and oxidation after long time use. The contact is safe and reliable by applying organic silicon grease for waterproofing and moisture sealing. Four basic units each of 25 pairs form the 100-pairs module. The positive and reverse connection terminals of the module are arrayed on the basis of YD322 chromatogram standard and printed with clear and full marks, which are convenient for jumpering and maintenance. The module unit line bank may turn around different Y-axes and open at an angle of more than 90 degrees, ensuring easy connecting of the main and distributing cables. The rubber sealing strips applied to the seams of doors and around the box effectively keep the rainwater out. The rubber sealing ring applied to the cable entrance hole at the base of the box prevents underground humidity from entering. The box is made of top quality cold rolled plate, stainless steel or aluminum alloy sprayed with pure resin. Its protective properties are up to the GB4208 standard