Sony 2X SEL20TC

(From Sony literature)

Double your focal length
Multiplies the focal length of the lens used by 2x without degrading optical performance, AF speed and precision, or operability. Light loss with the teleconverter is approximately 2 stops. An ideal way to extend available focal length range for sports or wildlife photography without having to carry additional large, heavy lenses.

Compatible lenses
The SEL20TC teleconverter is compatible with the following lenses: SEL70200GM, SEL100400GM.