What kind of motor driver should I pick for these motors?

I have 4 Pololu Sy42sth47 Stepper motors and I'm wondering what is the best way to drive these motors. Here are the specs...

Rated voltage (V): 4v
Rated current (A): 1.2
Resistance per phase: 3.3
Inductance per phase: 2.8
Holding torque: 3.17
Detent torque: 200
Rotor inertia: 68

https://www.pololu.com/file/0J685/SY42STH47-1206A.pdf thats the datasheet.

Firstly there is no rated voltage for steppers like that, they are low impedance current-driven steppers,
and suitable drivers include A4988 and DRV8825 modules. You can power the stepper driver modules at
12V, 18V, 24V, 36V, since they do active current control. Higher voltage gives higher speed, higher
torque at speed.

If there isn't rated voltage for steppers like this then why does the datasheet say there is one?

Stepper motor data sheets sometimes (as in this case) specify the voltage across the motor coil when the maximum rated current is flowing, but that is almost never of interest.