Sleep Master 12-Inch Gel Memory Foam Mattress, Twin Mattress layers include: 2.5" Gel memory foam, 1" memory foam (3 lbs.; density), 3" pressure relief foam and a 5.5" high density foam base Gel infused memory foam provides a cooler nights sleep The mattress is shipped in a small box and can take up to 48 hours to fully expand from its compressed state CertiPUR-US Certified Limited 5 year warranty