Those stepper drivers are most likely A4988 drivers. Here is the Pololu page for those drivers. On the page you will find instructions on how to properly set the stepper coil current (little pot). If you can hold your finger on one for a couple of seconds, it is fine, but it would be best to set the current right for your motors (within the limits of the driver and or motor). In this ad there is a photo of the orange version of the A4988 carrier board for comparison with yours.