50kw propane generator. We have run it for 5 day straight after the hurricane last year knocked power out on our processing plant. It ran a 4000 cubic foot freezer, a 2500 cubic foot carcass cooler, a 1000 cubic foot freezer, and lights the whole time without problems. It comes with the transfer switch. It generates 220 amps of continuous power day and night. I run it for 2 hours once a month to make sure it is in good working order.