... 3)fireproof safe heatproof 4)all kinds of surface box 1)Model: CY2042)Material: PVC surface box3)Sizes: 3"x3" ( ... manufactures all kind of pvc surface box , junction box , switch box , elecrical box . 1) good insulation characteristic, good insulation property, good fire-resistant2)no rust ... will very happy to be service of you . inner box , pvc material, 86x86x33mm, black or grey color, M4 screw.