What is the switch on side of model 20 jc Higgins pump shotgun?

The switch on the side of the Model 20 JC Higgins pump shotgun is typically the safety mechanism. This safety switch is designed to prevent accidental discharge by blocking the trigger mechanism when engaged. It is usually located near the rear of the receiver for easy access by the shooter. Engaging the safety ensures that the shotgun cannot be fired until the safety is disengaged.