LENRD stands for Low-End Node Reduction Device. As you may know, a resonance bump in a room's frequency response is called a room node.
The MegaLENRD Bass Trap is just a bigger version of the original best-selling Bass Trap. At twice the width (extending 2' along each wall, not 1' like the standard LENRD), the MegaLENRD is substantial enough to handle low-frequency problems in rooms of any size. It is the only broadband absorber effective below 50hz! Churches and critical listening facilities rave about the results provided by MegaLENRD. Available by special order only.