The new, High Speed, Full size, HV, Coreless tail servo from BK.

Check out the specs:
Specs:
Operation Voltage: 6V – 8.4V
Weight: 68g (2.4 Oz)
Dimensions: 20mm x 40mm x 37mm
Frequency: 760us/333 hz
Gear Type: Metal
Motor Type: Coreless

Torque:
8.4kg/cm (116.7 oz/in) @ 6V
9.6 kg/cm (133.3 oz/in) @ 7.4V
10.6 kg/cm (147.2 oz/in) @ 8.4V

Speed:
0.035 sec/60 @ 6V
0.032 sec/60 @ 7.4V
0.030 sec/60 @ 8.4V