Grand Bass are in-ear headphones that can reproduce powerful deep bass and crystal-clear sounds. This is enabled by the 10-mm-diameter ETEM driver and a composite diaphragm made of WFC paper and PU-2 layers, as well as by the front and back ducts with optimized airflow resistance that ensure smooth diaphragm movement. The rear housing uses machined aluminum that is hard enough to suppress unwanted vibration generated from the driver yoke. The rear duct necessary for the semi-open structure features a dynamic and edgy design, which successfully embodies the image of Grand Bass's powerful bass.