Compatibility: This lens is only compatible with fixed focal length L-series lenses 135mm and over, as well as the EF 70-200/2.8L, EF 70-200/2.8L IS, EF 70-200/4L, and EF 100-400/4.5-5.6L.
Features: Aluminum Case Resistor 100w;Aluminum Housed Resistor 100w;wire wound resistor 100w 0.2 ohm;resistor for LED PCB;resistor for converter speed control