The 3M heat shrink wall bushing type WMD is used to seal telecommunications cables in wall and duct penetrations. It enables the gas- and water-tight introduction of cables and pipes in buildings. It can also be installed as a reserve bushing to allow cables or pipes to be inserted at a later date. The corrugated surface is coated with a special sealing material, which provides a permanent water seal when the penetration opening is closed with mortar or cement. Suitable for masonry walls up to 480 mm thick.