Class O is a flexible, closed cell, elastomeric, nitrile rubber insulation. It is a highly efficient method of insulating hot and cold water services, chilled water lines, heating systems, air conditioning ductwork and refrigeration pipework for frost protection, energy conservation and condensation control. Temperature range : -50 to 110°C. Thermal conductivity : ≤ 0.034 W/(m.K). Water vapour permeability : ≥10,000 μ. Euroclass - tubes : BL-s3,d0. For metric copper tube use. 15 mm = 5/8" 22 mm = 7/8" 28 mm = 11/8" 35 mm = 13/8"v 42 mm = 15/8"