The GeoStone Retaining Wall System consists of two units, a 36 lb and 72 lb module.  They are typically used independent of one another but can be used together in banding or true ashlar patterns.  Between the two any requirement of an SRW system  can be achieved.  Most other systems accomplish this with twice as many units or more, resulting in a higher manufacturing and inventory cost.  The GeoStone concept is to keep it simple.