TB-200A Thomas and Betts, Challenger and Westinghouse Generator Interlock Kit 150 or 200 amp panels Generator Interlock Kit for Thomas and Betts, Challenger, and Westinghouse Panels 1 to 1 1/8 inch spacing between main and branch breakers Met lab listed E113887 Includes Interlock, Drill bit, labels and generator breaker retainer PLEASE Verify panel type by checking second picture