1.It is up to 15 years long life time 2.It is durable,recyclable and safety 3.Reasonable stress and large bearingcapacity 4.Improve working efficiency and save labour power 5.Largeand saftey operating areal 6.Keep exactly straight 7.Corrosionprotection alternatives 8.Open thread and covered thread.9.Adjustable telescopic, each having a series of maximum extendedlengths and each having differing endplate configuration