Yet another popular Zinus mattress that is getting extremely good reviews and ratings from consumers. The Zinus Sleep Master Ultima Comfort Memory Foam Mattress is very affordable and, for most owners, very comfortable. It also uses green tea extract to help maintain freshness and some of the traditionally petroleum-derived ingredients have been replaced with natural plant oils. In addition, the foam is CertiPUR-US certified (has met stringent standards for content, emissions, & durability). Some people find the edge support a little weak however and the mattress sometimes does not expand to the full advertized height.