The NPS 30A Transfer Switch (NTS-30i) is a shore/generator transfer switch built for mobile generator installations. It uses the industry standard "break before make" design along with a hardware interlock, which prevents power coupling between your generator and shore power. Easy-to-read diagnostic LEDs show you where the power is at a glance, so you can skip the volt meter and never need to open the enclosure. Backed by more than 50 years of combined RV experience at NPS. Features:• Shore/Generator Transfer Switch - Built for mobile generator installations • Break Before Make - Industry standard design for safe switching • Hardware Interlock - Prevents power coupling between generator and shore power • Diagnostic LEDs - Easy-to-read indicators show where the power is • Faster Diagnostics - No volt meter needed and no need to open the enclosure • 30 Amp Rating - Designed for 30 amp applications • Compact and Lightweight - 9.25" x 7.28" x 4.2" and just 1.5 lbs Break before make with hardware interlock Diagnostic LEDs show where the power is No volt meter or opening the enclosure