The Atlas A-Line EJW115X-B is a single 15" passive subwoofer in an optimally designed and constructed sealed Baltic birch enclosure.  This design provides even sound distribution at all distances.  The EJW115X-B is designed to be used with a EJ2003-B full range line array system.  The EJW115X-B needs to be used as a part of a pair of ELIJAH systems where an EJW115A-B can be used to provide power to the EJW115X-B and two EJ2003-B units.