these will cause an error if directly connected to a Panasonic camera - use basic adapters instead.
the most common chip used is a Dandelion programmable chip which you can buy separately and glue to a basic adapter.
search Ebay for cheaper Chinese versions
manual aperture-control lens adapters
mainly for use with lenses without aperture rings - eg. Nikon G, Minolta AF, Pentax K, Canon EOS
if you use an adapter without aperture control on these lenses, the aperture will be fixed wide open unless you stopped it down on a dSLR of the same brand by holding down the DOF preview button as you removed the lens - the aprture will then be fixed at the aperture set prior to removal of the lens.
0.71x focal length reducer = adds 1 f-stop more light and allows almost full frame field of view on APS-C cameras (become 1.09x crop factor) while MicroFourThirds cameras will have an effective 1.42x crop factor
the EOS adapter will also allow aperture control, OIS, EXIF, fast PDAF (on E-M1) and very slow CDAF (for post-2006 EF lenses)