The Olympus EC-20 2x Teleconverter doubles the focal length of any lens it is attached to from the wide selection of Four-Thirds and Olympus E-System lenses.
If you think about it, suddenly your Zuiko ED50-200 f/2.8-3.5 SWD lens (which covers 100-400mm in 35mm format) becomes, in effect a 200-800mm lens (in 35mm format). This converter saves you both time and money.
Small, compact and portable high-performance optic
Extends lens performance - allows you to bring subjects even closer to your camera
Does not inhibit mobility since it is only a small addition to the length of the master lens