This was an compatible replacement for my transfer switch in my 2007 FourWinds Windsport 33BI spent $350 troubleshooting the part itself to find from the factory it was sent with a failed circuit board.It would have cost me another $725 in labor to wait on a replacement and have it installed.The transfer delay circuit board had a poorly soldered J1 jumper. Two jumpers on the small 2" x 1" circuit board behind the bus in the box connect to AC power and two to DC to trigger a physical switch from the 50Amp Shore power to the Generator. Unfortunately the 12v DC jumpers never signaled.The only saving grace was the small circuit board in my old transfer switch was the same size/part/function and could be swapped. And my electrician knew his job well and offered up the diagnosis, proof, and fix.The board/part didn't undergo even basic QA from the factory. The Jumper wiggles to the touch, and the solder clearly wasn't done well.