A great advantage of Micro Four Thirds cameras is their small size and weight, but to maintain that advantage, you need small, light lenses. This wide-angle Panasonic Lumix G 14mm F2.5 ASPH Lens (28mm equivalent in 35mm) is about as small and light as you can get in this format--it has a diameter of just 2.19", length of 0.81" (from the tip of the lens to the base side of the lens mount) and it weighs a mere 1.94 oz.
And what a lens! It features 6 elements in 5 groups, including 3 aspherical lenses, a fast f/2.5 maximum aperture, and uses 7 diaphragm blades to form a circular aperture diaphragm. It has an angle of view of 75° and focuses to 7" (18 cm). This lens is compatible with Lumix G Micro Four Thirds cameras.