SUB-WOOFER BOX - ZERO PORT OPTION This driver is built similar to the active woofer and is a good match to the SB29SWNRX-S75 10" subwoofer. In 0.75 to 1.0 cubic foot with that woofer you have an F3 of about 35Hz. It also mates well with the SB29NRX75-6 10" woofer. In 1.0 to 1.3 cubic foot, your F3 is 38Hz. Using a plate amp with a low frequency boost, you would go even lower. (see DW-50 for additional 50g weights). Hard paper cone for improved piston operation (made in-house) Cast aluminium chassis for optimum strength and identical SB29, NRX series woofer style Low damping medium hardness rubber surround for improved dynamic linearity and mechanical stability Moving mass 455g. Includes screw to add more if required.