• Suitable for selected Micro FourThirds Lenses
• Includes both 16mm and 10mm Extension Tubes
• Full and perfect diaphragm (aperture) coupling
• Full and perfect TTL/EE Metering
• Use Individually or Combined

Extension tubes are designed to enable a lens to focus closer than its normal set minimum focusing distance. Getting closer has the effect of magnifying your subject (making it appear larger in the viewfinder and in your pictures). 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.

These DG extension tubes have no optics. They are mounted in between the camera body and lens to create more distance between the lens and CCD plane. By moving the lens further away from the 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.

See here for full compatiable list