This is a genuine Hitachi replacement part,it is sold individually.
Switches are commonly replaced parts in power tools.
A switch handles on/off and variable speed functions. They also have a role in electric breaking; they can momentarily reverse electrical polarity. Because switches use mechanical internals, they will degrade and wear out over time, eventually requiring replacement.
Some common signs of a broken or failing switch are:
(1 P Pillar Type)