Polk lists the 120hz crossover is to the "Subwoofer Array Driver Complement " in that speaker, from the "Mid-High Array Driver Complement"
Seems like they forgot they need something in that cabinet to be an actual woofer !

It's a wonder everyone of those towers made aren't fried.
- Mid-High Array Driver Enclosure TypeSealed
- Mid-High Array Driver Complement• (2) 5.25" (13.34 cm) d (Round) Dynamic Balance drivers with polymer composite cones and rubber surrounds - Midrange
- Subwoofer Array Driver Enclosure TypePowerPort Plus Bass Venting
- Subwoofer Array Driver Complement• (3) 7" (17.78 cm) d (Round) Dynamic Balance drivers with polymer composite cones and rubber surrounds - Subwoofer
- Front Array Driver Complement• (1) 1" (2.54 cm) d (Round) Dynamic Balance silk polymer composite - Tweeter