... steel plate4.0-5.5 kgRust easily, distort easily,heavy weight3-5 yearsCommon anti-rust aluminum alloy2.5 kgRust ... Stainless steel3.5-5.5 kgCorrosion resistance, rust difficultly ,heavy weightOver 10 years Fluorocarbon Coating aluminum alloy2.2 kgNo ... flame retardant resistance, nylon bracket,rivet connect.Advantageslight dead weight,fast speed of rotation,stronger preservation,high efficient exhaust ...