OLYMPUS ZUIKO DIGITAL 1.4x Teleconverter EC-14 for Four Thirds Mount

Overall, the EC14 is compatible with the Zuiko digital 14-54mm f/2.8-3.5, 50-200mm f/2.8-3.5, 300mm f/2.8, and 50mm f/2.0 (f/2.8 and up) lenses.

eBay