17g Digital Metal Gear Reverse Servo with 600mm (23") Lead from Freewing - MD31172R-600
This servo is used on various Freewing jets. It can be used with other aircraft with compatible specifications (see below).
Features:

Lightweight, efficient high torque digital metal gear reverse servo perfect for mid-sized to large EDF jets

Includes:

Freewing 17g Digital Metal Gear Reverse Servo with 600mm (23") Lead
4 mounting screws
2 servo horns