How strong is the edge support?

Strong, scoring 8.3 out of 10. A foam encasement wraps the 2550-coil system, giving the border roughly three times the support of a bare foam edge, and we measured edge sinkage of 3.26 inches when lying near the rim, firmer than the field. You can sit on the side to dress or sleep right to the edge without the roll-off feeling. For couples who use every inch, that reinforced rim keeps the full surface sleepable.