This product listing is for two different circuits, both of which adjust the End Point settings of any servo connected to them.  One is a Servo End Point Expander, the other is a Servo End Point Reducer.  Both work with any kind, type or brand of proportional servo, either analog or digital.  The only type of servo with which they will NOT work is a retract servo, and that's due to the way in which retract servos are designed to work
 
The Servo ATV Expander/Reducer is primarily intended to make it easier to adjust the linkages of models that have more than one servo that are controlled by the same channel on the receiver, like models with multiple gear doors or models that have complicated flap systems.  By increasing or reducing the amount of travel on the servo connected to these devices, you can either increase or decrease the movement of a single servo, while allowing the other servos connected to the same channel the  movement that is set using the End Point Adjustments in your transmitter.  A small trim pot near the top of the board is used to make the adjustments to the end points of the servo connected to them.  The range is adjusted in both directions equally, so it may be necessary to reposition your servo arm after installing this device to maintain proper movement of the servo within the new range set by the circuit.  Maximum adjustment is approximately equal to 50 "steps" or percentages in your transmitter's menu.  Minimum adjustment is 0 steps.
 
Use the drop-down menu in the upper right corner of the page to choose between the Expander or the Reducer.  Operation is easy and automatic, the only thing you have to do is adjust the end points of the servo as required by your installation.
 
DOWNLOAD: Servo End Point Expander Instruction Manual
                     : Servo End Point Reducer Instruction Manual