M series can be installed by YZ1515x,YZ2515x,DG-1 and DG-2 four kinds of pump heads.Flow speeds can be adjusted by hand through switching knobs, instead of the traditional way of membrane keypad, which reduces obviously the failure rate, or by automatic control through the external controller interface, with three available modes: 0-5V, 0-10V and 4-20mA. Memory function is also available in the product in case of power off. Besides, switching knobs are designed clearly so that it is easy to operate for customers.