Inseesi Metal Mount Auto Focus AF Macro Extension 13mm Tube +21mm Tube+31mm Tube for Canon EOS EF EF-S 1D X 60D 7D 6D 5D Mark III (Silver) 1. Designed to enable a lens to focus closer than its normal set minimum focusing distance. 2.Auto Focus Macro Extension Tube for CANON EOS EF EF-S 1D X 60D 7D 6D 5D Mark III 3.Free style of three tube: 13mm, 21mm, and 31 mm - which can be used individually or in any combination to obtain the desired magnification. 4. Designed with circuitry and mechanical coupling to maintain auto focus and TTL auto exposure with Canon lenses,which activate the cameras AF system properly. 5.Perfect for flowers, insects, coins, stamps, and any close-up shots you want to take.