... flexible 4.Fire proof, MoistureproofBellsafe-flex adopting NBR/PVC as the main raw material, is an environmental ... -proofing property.The standard products are balck,with sheet,tube two types. Usage :Bellsafe-flex (Class B1 ... apply in HVAC system Specification: Main material : NBR/PVC ID size:1/4", 3/8", 1/2", ... can beat any competitorPacking photo : NBR/PVC Insulation tube easy for installation