Serta Pearce Plush Mattress Set, Twin XL The Serta Perfect Sleeper is the Only Official Mattress of the National Sleep Foundation (NSF), designed to help address 5 common sleep problems Cool Action Gel Memory Foam: in Perfect Sleepers for the first time, this revolutionary foam delivers pressure relief while reducing heat build-up Custom Support Individual Advantage 886: features ventilated wrapped carbon steel coils that react individually to provide conformability Mattress Set includes Serta Perfect Sleeper 9" Stable-Base Foundation Set measures 79.5 inches long by 38 inches wide by 21 inches high; 10 year manufacturers warranty