B00GBQ91N4 Nikon D610 2X Teleconverter (4 Elements) + Nwv Direct Microfiber Cleaning Cloth.

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4-elements
Multi-coated Optical Glass with anti-reflection coating
Doubles focal length of lenses (NOTE: NIKKOR lenses designated as G AFS will autofocus. NIKKOR lenses designated as G will NOT autofocus. All other NIKKOR lenses – AF, AF-D, AFS, etc – will autofocus.)
Manufacturers’ Lifetime Warranty
Item Includes: Case, Protective Lens Cap, Nwv Direct Micro Fiber Cleaning Cloth