The purchase of pneumatic hose should note the following four aspects: 1. Pipe material: PU tube, Nylon tube, the inside of the tube diameter size: customary to the outer diameter of the tube as the size of the pipe, commonly known as "pass diameter. " The public commonly referred to as DN is not the same thing, the user purchase should pay special attention to. 3 the uniformity of the thickness of the tube, the tube uneven work easy for leaks abrasive manufacture . The wall thickness of the tube should be considered used in pipe joints in the form of an optional hose clamp fittings and card sets of pipe joints should pay attention to the tube diameter size; should pay attention to the outside of the tube non woven abrasive , the use of plug-in tube fittings diameter size