Aftermarket Trigger Type On-Off Switch used mainly on worm drive skil saws and other 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, but these switches are made to last longer. This Trigger type switch has 4 internal terminals. Replaces Skil part number 2610321608. These are as good as the genuine Skil part, at a much lower price!