Precise control over fiber optic cable with a length ensures good tensile strength and temperature characteristics. 2, loose tube material itself has good water resistance and high strength, tube filling special ointment, a critical protection of fiber good resistance to stress and softness. 3, PE jacket has good resistance to UV radiation performance and resistance to environmental stress cracking resistance. 4, the following measures to ensure the cable watertight: a) single wire center stiffener; special fiber cream filling inside b) loose tube; c) 100% cable core filling; d) GYTA sided coated aluminum (APL ) to improve the cable barrier to moisture; e) Good water blocking material to prevent the cable vertical seepage.