HMP40223221 is a Mercury Ballast with magnetic chokes work on the self-inductance principle and limit lamp current and lamp wattage with a high level of efficiency. The chokes are required to operate high-pressure discharge lamps. The impedance of the choke is set to match the particular type of lamp which ensures that the correct lamp performance is achieved, in some cases, a choke can be used for more than one lamp. It offers supply voltage and supply frequency influence choke requirements and so the operating devices should be matched to the current supply voltage. It is possible to expand the scope of application by using chokes with several voltage tapings.