Meike MK-N-AF1-B Electronic Mount Auto Focus Macro Extension Tube Set Ring for Nikon D7100 D7000 D5200 D5100 D5000 D3100 D3000 D800 D600 D300s D300 D90 D80 Built-in electric pins, Support accurate Autofocus. Combined with 3 tubes in different length: 12mm, 20mm, 36mm, tubes may be combined for greater magnifications. Upgraded circuitry to work better with digital SLRs cameras and SLR lenses. Superior lock pin which can tighten the tube joint. Perfect for macro shooting.