The hood for this lens is the same as that used for the 9-18. So if you have that one, you can double up. If you don't have it the cheapest I saw it was at RainbowImaging. They have impossibly fast service and free shipping over $10 (although the hood is slightly less - so buy something else).

Fits perfectly, quality seems good. Box shows JJC which is what you see on ebay.

Olympus LH-55B Lens hood, Olympus M.Zuiko ED 9-18mm f4-5.6 lens