Naylor MetroDrain perforated twinwall pipes are manufactured from HDPE for high performance and high strength. For non-pressure surface and sub-surface water drainage, each twinwall pipe has a corrugated external side for strength and a smooth internal bore for improved water flow. BBA approved and compliant with Highways Agency regulations, Naylor twinwall pipe is easily cut to the length required. MetroDuct Perforated Twinwall Pipe Specification Length: 6mDiameter: 225mm  Naylor MetroDrain Perforated Twinwall Pipe 225mm x 6m HDPE 71313