Brake light switch, pressure activated. This switch is an easy way to add brake lights to your vehicle, since the switch powers the brake light system using the hydraulic pressure from the brake line. Ideal for use w/ after-market pedals that don't have provisions for a brake light switch. Eliminates the hassle and complexity of modifying pedals for a mechanically operated brake light switch. This switch can also be used as a safety feature to prevent the engine from starting w/o the clutch pedal depressed (w/ hydraulic clutch & manual transmission). Plumb this switch in the clutch line and run the small wire than goes from the start switch on the ignition to the starter solenoid through this switch. This will prevent the engine from turning over, unless the clutch pedal is pressed in.