I have experience with BOTH models.
The model with '12' in the number is there backup camera version. The monitor supports pairing to 2 cameras. You could for instance have Camera#1 mounted high at the back of the trailer for help in backing in and then buy a 2nd camera to mount at the back of your SUV or Truck to help you do the hookup. What you CANNOT do very well with this model is use it for a pseudo rear view mirror while you are towing down the highway. The reception and processor will continually freeze and drop out. Basically, the '12' model is good for backup only.
The model with '48' in the number is their 'observation' camera version. The monitor only supports pairing to one camera and it must be the camera model that also has a '48' in the model number. One thing you will notice on the '48' is that BOTH the camera and the monitor each have a little popup antenna. On the '12' only the camera has the antennae. The '48' has a better range and processor and can easily keep up for use as a pseudo rear view for watching traffic as you tow down the freeway. As a bonus, the monitor on the '48' appears sharper/clearer to me.
I use the '48' in the Forest River factory installed spot high up on the back of the fifth wheel. The angle is set so that I can monitor traffic behind me as I tow.
