We manufacture surge protector device; LDY series signal surge protector device; LDY-D230 subtle surge protector devices; Lightning protection box LDY plug type series surge protector device is applicable for B C D three classes protection, it adapts to LPZ1-LPZ2 lightning protection area. LDY-10D with D protection grade satisfying protection requirement about end of electric equipment. LDY-20C with protection grade are almost applicable for the lightning surge protection of power supply system of building, floors or indoor distribution box, branch cabinet of low voltage switch cabinet. LDY-30B LDY-40B with B protection grade are installed in the low voltage inlet main switch cabinet of the buildings.