Designed for use Only with Kohler Generator sets equipped with the RDC2 controller. The transfer switch uses Square D Circuit Breakers QO, QOA, QOC, QOP, QOT. Load Center Spaces 16. Tandem breakers 8 . The Kohler Transfer Switch is brand new and still in the box. I have more than one to sell . Normally they sell for $900.00 New. Selling by a local Electrical Contractor.