Medium Density Fiberboard (MDF) back box for the IWS105 inwall sub, works with the IWS100 sub, designed to fit any standard 16" stud bay. Cuts down on translational energy vibration between adjacent walls. The IWS105 sub is tuned to the BB-IWS10 back box. Not for use with ICS11,ICS10 and IWS82.
