DC motor control: voltage question


I try to build a motor control unit using Arduino.

The motor that I have to control is rated 4 to 6V, as described here : TKD 2CP-2511/4CP-2511 MC Motorised volume control | HIFICollective

I have 2 available Arduino DC motor control shields, but they are supposed to drive DC motor accepting 7V-12V for the first shield and 4.5V-12V for the second available shield.

My question is that I do not understand if it is (and HOW) possible to define the shield output voltage ??? in order to apply the appropriate voltage to the DC motor.

I have read the specs of the 2 shields and I do not see how to define the shield voltage output...

Can anybody help me ?

The available shields that I have are:

this one: 2x1A DC Motor Shield for Arduino - DFRobot
or this one: http://www.elecfreaks.com/wiki/index.php?title=Arduino_Motor/Stepper/Servo_Shield#Powering_your_DC_motors.2C_voltage_and_current_requirements

You don’t define it with the shield. You define it by what voltage you hook up to it. Hook up a 12V battery to run at 12V. Hook up a 6V battery to run at 6V.