The inner height, outer height and pitch of the same series of tow chains are the same, and the inner width and bending radius R of the tow chain can be selected differently. The unit chain is composed of the left and right chain plate and the upper and lower cover plate, each section of the drag chain can be opened, convenient installation and disassembly, no need to thread, after opening the cover plate, you can put the cable, oil pipe, gas pipe, water pipe and so on into the drag chain. Each section of the tow chain can be designed to be opened for easy installation and maintenance. Low noise, wear resistance, high speed movement. A separator can also be provided to separate the space in the chain as needed.