The Auto Extension Tube Set DG for Canon EOS Lenses from Kenko contains three tubes of different lengths--12mm, 20mm, and 36mm--which can be used individually or in any combination to obtain the desired magnification. They are compatible with Canon EF and EFS lenses.
The greater the length of the extension tube, the closer the lens can focus.
These Kenko Auto Extension Tubes retain auto focus capability with Canon AF lenses providing the effective aperture stays at f/5.6 or brighter.
12mm, 20mm, 36mm extension tubes work individually or in combination
Allows close-up macro photography with non-macro lens
Retains auto focus function when effective aperture stays at f/5.6 or brighter (f/8 or brighter on EOS 3, 1V & 1D cameras)

12mm Tube: 2.1 Oz (60 g)
20mm Tube: 3 Oz (85 g)
36mm Tube: 4.4 Oz (125 g)