These servos are definetelly one of the bestchoice for 48” 52” airplane and 450 size helicopter.
 
Dimensions: 0.31 x 0.93 x 0.87 in / 12 x 23 x 22mm
Weight: 0.72oz / 20.5g
Stall Torque (oz-in): 30.6@5.0v/ 36.7@6.0v/ 42.8@7.0v
Stall Torque (kg-cm): 2.5@5.0v/ 3.0@6.0v/ 3.5@7.0v
Speed (sec/60deg) : 0.11@5.0v/ 0.09@6.0v/ 0.08@7.0v
Motor Type: coreless Spline size M5-T21
System PWM
Gears Material: B/plastic, C/Metal, D/Met, E/Metal. F/Metal.
Recommended voltage range is 6 - 7V.