This switch is an Aftermarket Hammer Switch 16A-125V (Replaces Bosch 1617200048) and is used In Bosch rotary hammers and demolition hammers.Switches are commonly replaced parts in power tools. A switch handles all 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 tend to degrade and wear out over time, eventually requiring replacement.