Opteka Auto Focus DG EX Macro Extension Tube Set for Canon EOS-M/EOS-M3 Mirrorless Digital Cameras (10mm/16mm/21mm) Extension tubes are designed to enable a lens to focus closer than its normal set minimum focusing distance. Designed with all the circuitry and mechanical coupling to maintain auto focus and TTL auto exposure with Canon EOS-M cameras and lenses Contains three tubes of different length, a 10mm, 16mm, and 21mm Glass-free; Lightweight 1 Year Opteka Warranty