The set consist of three tubes of different length, which can be used in any combination or individually to obtain the different magnification.
This Extension Tube set provides 3 extension tubes that can be added between the camera and the lens, to make the lens focus at closer distances and produce higher magnification. Extension tubes are metal tubes with a rear-lens mount at one end and a camera-body mount at the other end.
This Extension tube set does not affect image quality as there is no optics inside. In comparison, a close up filters are often blamed for degrading image quality. It moves the lens farther from the film or digital sensor.
There are no electrical contacts in the extension tubes. Exposure and focus have to be adjusted manually. Aperture control is not available if you use a lens which does not allow you to manually adjust the aperture (Without an aperture ring).