Amazon.com Product Description
The Sigma 2.0x APO Teleconverter lens features a high performance optical design with six elements in five groups. It is optimized for use with long telephoto and telezoom lenses, and is ideally suited for use with the 70-200mm f2.8 APO EX HSM zoom lens. Since it uses 10-pin electrical interfaces, there is no loss of autofocusing speed when these teleconverters are used with compatible HSM type lenses. This model is dedicated to Nikon AF SLR cameras.
Product Description
Expand your Macro world with Sigma EX Apo Tele-Converters. By using the 2x EX Apo Tele-Converter, you can increase the magnification to up to 2:1 (twice life-size) or, retain same life-size reproduction at an even greater working distance, great for photographing difficult subjects like butterflies or small animals, which can be difficult to approach.