This kind of oil cylinder is called a sleeve-type telescopic oil cylinder. Its stroke is the sum of the strokes of each section of the oil cylinder. For example, the 4TG-E180*5390 oil cylinder you mentioned is a domestic oil cylinder, but it represents The meaning is the same as Hyva, 4TG means that the cylinder can extend 4 sections, the diameter of the maximum extended section is 180, and 5390 is the maximum working stroke of the cylinder. It is the total length of 4 sections of extension.