Macro extension tube set for SLR cameras with M42 lens mount is composed of 3 extension tubes - 7mm, 14mm, and 28mmwith male and female M42 screw mount adapters. Mount the tubes between lens and camera body to get your choice of macro ranges - 8 combinations in total. Made from metal. Mounting extension tube in between the camera body and lens will create more distance between the lens and film plane. By moving the lens further away from the film or digital camera sensor, the lens is forced to focus much closer than normal. The greater the length of the extension tube, the closer the lens can focus. Use this set with your normal lens and you will get the quality, which is as good as the original lens and the size, sharpness and versatility is perfect for the macro and close-up pictures. With all M42 mount lenses you will need to use manual focus and manual aperture while shooting.