... HF Acid and Alkali.ISOLATIONGood conductor,not insulateInclude steel liner,bad insulationGood insulation and securityDURABILITYLess than 20 years,glasses are fragile,need ... ,glasses are fragile,need change regularlyMore than 30 years,FRP plane skylight is anti-corrosion,not fragileECONOMYLow inveatment,high maintenance costLow inveatment ...