SB Acoustics SB29NRX-00 10″ Coated Paper Cone Passive Radiator
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.
Spec sheet: SB Acoustics SB29NRX-00 10″ Passive Radiator