The folks at Leerburg summed this bowl up best when they called the Road Refresher "the slickest no spill bowl I've ever seen".
In short, the bowl has a lipped cover to prevent spilling, and uses a floating plate to restrict the flow of water, while always leaving some water available. Originally designed for travel purposes, anyone can see that this bowl would also help a dog who digs or tips their water dish. It's even got a velcro bottom, so it can grip to car floor mats or carpets.
I had to laugh at one testimonial from a woman that had resigned herself to putting her dog's water dish in the bathtub, because he spilled so much water. This even cuts down on slobber up to 90%-bonus!