欧洲妇女成人淫片aaa视频,高清无吗,成人精品免费网站,国产精品久久免费视频,在线一二区,在线中文字幕播放,偿还的影视高清在线观看

Mining optical cables are made by inserting single-mode or multi-mode optical fibers into loose tubes made of high modulus plastic, and filling the tubes with water-resistant compounds. The center of the cable core is a phosphated steel wire or a steel wire rope extruded with polyethylene. A loose sleeve (or filling rope and signal line) is twisted around the center to strengthen the core and form a compact and circular cable core. The gaps inside the cable core are filled with water-resistant filling material, steel polyethylene bonded inner sheath, and blue flame-retardant PVC sheath to form the cable. The mining optical cable has a flame-retardant sheath, which can have a full section water-resistant structure to ensure good water and moisture resistance. The loose sleeve is filled with special grease to provide critical protection for the optical fiber.