This is 18090 Yikong 9g Servo Plastic Gear Torque for 1:18 Scale 4WD Brushless Remote Control Desert Off-Road Car?
which will keep the RC cars running in the right direction.

Description?
Analog servo: yes
Operating Voltage: 4.8-6.0vdc
Operating Speed: 0.14sec/60°(4.8v) /0.12sec/60°(6v)
Stall Torque: 1.5kg.cm at 4.8vdc / 1.7kg.cm at 6vdc
Cable length: 3.5cm
Size: 3.5 * 3 * 1.4cm
Plastic Gears: Yes

Package Information:
Package size: 3.5 * 3.5 * 1.5cm / 1.4 * 1.4 * 0.6in
Package weight: 10g / 0.3oz
Adhesive taps package

Package List?
1 * 18090 Yikong 9g Servo