Kenko intermediate rings with the transfer of automation that are designed to allow the lens to focus at a distance closer than its minimum focusing distance. 

Intermediate rings with AF and exposure are equipped with contacts transferring all information about the exposure parameters to the camera body. All automatic camera modes will work with them. For newer lenses equipped with an AF engine, it will also work. Older lenses in which the AF drive is transferred by means of a mechanical clutch will work in manual focus mode.

The MK-N-AF1-B adapter  ring set is equipped with contacts transferring all information about exposure parameters to the camera body. This means that all automatic camera modes will work with them. New lenses equipped with an AF engine will also function. In contrast, older lenses in which the AF drive is transferred by means of a mechanical clutch will work in manual focus...

MeiKe adapter rings in the econo version (with a plastic bayonet) are an accessory designed for micro DSLR lenses useful when shooting at short distances, at higher magnification.

MeiKe intermediate rings with an aluminum bayonet  are an accessory designed for micro DSLR lenses useful when shooting at short distances, at greater magnification.