Separate' 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. Now, thanks to this Bass Traps, you can achieve the low frequency sound control easily.
This bass traps are substantial enough to control nodes have always been expensive to buy or intricate and time-consuming to build, but not anymore! The bass Traps are extremely effective at smoothing out low frequency room nodes.