Product Description Description： 1. It moves the Lens from the Film or Digital Sensor, the Closer the Focus is, the Greater the Magnification 2.This high quality automatic macro Extension Tube Set is designed to enable a lens to focus closer than its normal set minimum focusing distance. 3.They are exceptionally useful for macro photography, enabling you to convert almost any lens into a macro lens at a fraction of the cost while maintaining its original optical quality. 4.The DG extension tubes have no optics. They are mounted in between the camera body and lens to create more distance between the lens and film plane. By moving the lens furthur away from the film or CCD sensor in the camera, the lens is forced to focus much closer than normal.The greater the length of the extension tube, the closer the lens can focus. 5. It comes as a set (10mm+16mm+21mm).It contains 3pcs tubes in different length 10mm/16mm/21mm, and each tube can work alone or combination . 6. It is with electronic contacts, which make it support automatic focusing,automatic exposure,etc.It enables you to use all shooting modes of the camera,exposure compensation is required. Electronic contacts is well-built, smooth transmitting signal. Specifications: Model: EXT-EOS-M Compatible camera:EF-M Mount Adapter focal length:10mm/16mm/21mm Material: plastic and metal Weight:110g Package List: 1 x extension tube set