welcome to our website. Product use: double telescopic column of hydraulic support is a part which jions the beam and base,bearing the load of crown plate,It is the main load bearing part,including two forms ;all-hydraulic and mechanically lengthening. Contact us if you need more details on Used Hydraulic Cylinder. We are ready to answer your questions on packaging, logistics, certification or any other aspects about Hydraulic Oil Tank、Multi Stage Hydraulic Cylinders. If these products fail to match your need, please contact us and we would like to provide relevant information.