Designed for use in RVs with 30 Amp (120Vac) or 50 Amp (240Vac) service. When plugged into the shore power, it will automatically provide AC power to all AC appliances. To operate your appliances from an onboard generator or alternative Power source, simply start them, and PMTS 30A or PMTS 50A will automatically transfer the electrical power to AC appliances. They also feature a time delay of 20-30 seconds to allow the generator voltage to stabilize. PMTS will Automatic Transfer between 2 - 120V/240Vac inputs to a single 120V/240Vac output2 year warrantyAvailable in 30 Amp (120Vac) & 50 Amp (240Vac) sizesIdeal for uses with RV, Off-Grid, and with Back-up Power solutions12 Volt DC Relay^PMTS-30: 8"Lx8"Wx3"H Knockouts: 7/8"(2) & 1"(1)^PMTS-50: 8"Lx8"Wx4"H Knockouts: 1"(4) & 2"(1)