Auto Focus Macro Extension Tube Set for All Nikon SLR Cameras Designed to enable a lens to focus closer than its normal set minimum focusing distance. Magnifying your subject (making it appear larger in the viewfinder and in your pictures) Tube Set Includes: 12mm, 20mm, & 36mm extension tubes Designed with all the circuitry and mechanical coupling Lightweight design Tubes can be used individually or in any combination to obtain the desired magnification