How is the edge support on this mattress?

Strong, scoring 9.8. The foam-encased coil system wraps the border in a dense foam rail that gives far more support than an unreinforced foam edge, so the bed holds firm when you sit on the side to dress or sleep to the perimeter. On a tall 14-inch pillow-top that reinforcement matters even more, keeping the plush surface from collapsing or rolling you off, so every inch of the sleeping area stays usable on a shared bed.