1.Soft penetrated pipes 2.ISOO9001:2008 3.High quality 4. ... . Well connect with all kinds of soil.Usages: Drainage for airport, railway, highway, sports field, greenabelt of garden etc ... . Drainage for tall dam of mines, ash dam of fire, rubbish ... burying field etc. Drainage for tunnel, retaining wall, roadbed, road surface etc. S ...