The Commlite AF Extension Tube Set (Plastic version) can perfectly transform your Lens into a Macro Lens for great Macro shooting. It drives the lens by film or digital sensor and does not affect aperture and image quality. Meanwhile it is combined with 3 pieces of different tubes (length: 12mm 20mm 36mm) which can either be used separately or in any combinations(totally 7 different combinations) to satisfy your different magnification requirement. Furthermore the tube is electronic one that can achieve functions of Auto-focus as well as TTL auto exposure by working with all AI Nikon lens. Compatibility: All AI Nikon lenses and Nikon DSLRs Features: 1. Support accurate TTL & Autofocus; 2. Built-in electric pins; 3. Compatible with all AI Nikon lens and Nikon DSLRs; 4. Combined of 3 tubes with different length of: 12mm 20mm 36mm; 5. Made of high-quality ABS material that is more strong; 6. Upgraded circuitry to work better with digital SLRs cameras and SLR lenses. 7. Superior lock pin which can tighten the tube joint; 8. Perfect for macro shooting. 9. High quality and compact.