Rover 5 - 4 Channel Motor Controller: PWM Frequency

I just got hold of OddBot's Rover 5 platform and the 4-Channel Motor Controller.  I'm still fairly new to all this and I'm not sure what PWM frequency to use for the controller.  The datasheet that I have doesn't specify so I'd appreciate any advice you can give me.

Many thanks.

Thanks OddBot.I wanted to be

Thanks OddBot.

I wanted to be sure that I wouldn’t damage the controller.