Panasonic DMW-GWC1GU Wide Converter for H-PS14042 and H-H014 22 mm (electronic)
I use the converter to the 14mm prime lens. While I find that 14mm at full aperture comparatively (Oly 9-18mm) sharp, so be the focus with the converter in the entire edge area (not just the corners) but strongly after. The 9-18mm Oly makes it better