A mattress embodying a removable exterior top and interchangeable segments (e.g. foam) positioned above a mattress base support portion and below the removable exterior top. The removable exterior top may be replaced with new or different removable exterior tops. Also, users have the ability to vary softness (i.e., firmness) or other characteristics (e.g., foam component construct) across the mattress by arranging or rearranging the interchangeable segments located directly below the removable and interchangeable mattress top. An exemplary base support portion may include a heavy duty pocketed inner-coil unit for motion transfer support and increased airflow.