Kenko Uniplus Tube, Extention Ring for Canon EOS AF Mount.

KENKO UNIPLUS TUBE (extention ring) is an accessory exclusively designed for use with standard AF lenses to shoot subject at closer distance with higher magnification. Magnification ratio for TUBE 25 is about 1/2 with 50mm standard lens. Perfect coupling with automatic aperture, TTL metering and AE mechanism.
Note: not compatible with EF-S Lenses.