The HWLB4 series connecting rod float ball level switch is fixed in a closed stainless steel or plastic tube, one or more magnetic spring switches, and then the fixed ring fixed the float ball on the tube and the position related to the magnetic tube switch, so that the float ball floats up and down in a certain range. The magnet in the float ball is used to attract the contact of the magnetic spring switch, and the product can disconnect and turn on the action to control the liquid level. The PFA material shell is resistant to strong acid and alkali corrosion, the resolution is 0.05/0.1mm, and the high-precision liquid level detection communication interface is rich, which can be customized on demand.