I have an ordinary adaptor. It only works for old Nikon lenses with aperature ring. And there is no metering and one can only use manual mode in Canon camers. If one plugs the new G lenses into the Canon camera, the aperature cannot be controlled. The worst thing is that the only possible aperature of a G lens is the smallest aperature. i.e f22!!!!

According to the description, it provides a mechanical connection between the lens, the aperature can be controlled and the body but retains automatic metering for aperture priority mode! That great!!!