... 1). Toughness: If you bend ,can not be easier to break2).Hardness: Under pressure ability, high impact resistance3).Fire-resistance ... insulation, which resist 25kv voltage , assuring a safe system6).Installation: easy to open and close ,convenient push-pull,installed with solvent ... and exchanging6).Lifetime: Normal use life can be up to 50 years 7).They are suitable for the chemical industry ...