The wide conversion lens from Sony for the 16mm lens.
According to Sony:
Increase your creative vision with a choice of ultra-wide angle and fisheye conversion lenses for your NEX-5/NEX-3 camera. Attaching in moments to the camera’s standard 16mm F2.8 ‘pancake’ lens, both convertors increase your field of view without compromising optical performance.Features VCL-ECU1
* Adaptor for E16mm F2.8 pancake lens provides ultra-wide field of view
* Sleek, high quality design
* Easy-attach bayonet mechanism with lock for quick, secure fit
* High definition optics for uncompromised imaging performance
Please be aware that the features/specifications can differ from country to country.