Some 180° servos require PWM values in the range of 500-2500uS to work in the full range.
When using a PWM signal from a standard receiver with a range of 1000-2000uS, you will not use the entire 180° range of the servo.
This servo expander expands the classic 1000-2000uS range to the 500-2500uS range.
Just connect it between the RC receiver and the servo.
Key Features:
Input voltage: 3.6-16V
PWM input range: 1000-2000uS
PWM output range: 500-2500uS