We bought two Motorola RDV2020s on eBay. They are not cheap, but the clarity is much better than the cheap two way radios. You have a choice of two channels (if you find that one is full of static or in use). They have quite a range and work well for us. When I am backing up, I place it on the console and just listen. She has the PTT (push to talk) button depressed all of the time, so that she can immediately communicate to me to stop or change direction. It has worked well for us for over 10 years now.
Scott