Transmission line Subwoofers?

Does anyone know of any commercially available subs that use a transmission line design?
There are a bunch of DIY subwoofer designs on the web using TL enclosures, including one that (I believe) Teres Audio will build for you. If memory serves, Wisdom Audio (used to?) sells a finished product, as well. Not a lot of choices out there AFAIK.
Bag End subs
Wisdom still does. Check their website.
I believe Bag End uses sealed cabinets, unless they've changed designs.
I have no direct experience with them, but TBI Audio Systems has subs which use what they call ETL (Embedded Transmission Line) technology.
My local high end dealer has TBI subs set up for demo. I find them a little quirky sounding. I think some folks will love the "bloom" (lousy descriptor, but best I can come up with) that they provide in the bass, but not entirely convincing to me. Certainly not bad, and lots of power from a small enclosure, but definitely a try before you buy product IMO.