CANON EF 24-70MM F2.8 L II USM LENS. THIS WILL ONLY FIT CANON EF 24-70MM F2.8 L II USM LENS (MARK 2). POWER DIAPHRAGM UNIT FOR. 100% MADE BY CANON INC. If your getting Error 01 on the LCD, a communication error between lens and body, then this should fix the problem.