Transmission line speakers!

I had a pair of Clements Audio RT-7 that I used for years. Great speaker. 2-Way with a true ribbon tweeter and a small transmission-line loaded woofer. Narrow baffle. Nice sounding speaker. I auditioned it against a comparably sized and priced Ohm Omni speaker at the time and chose the Clements.

I may still be using them today if the cosmetic/aesthetic were better. The early RT-7s had a foam wrap around the whole column and the column simply sat in a base. The speaker column had a beveled edge on the bottom and the base had an opposite beveled edge to accept the speaker column. Wasn't particularly stable or instill a great amount of confidence in the junction between speaker column and base.

Later versions of the Clements Audio RT-7 did away with the column/base setup and also changed the finish from a foam wrap to finished hardwood veneer. 

Transmission lines are still ported speakers, although when properly designed tend to sound a bit better. Still nothing compares to a properly designed acoustic suspension design to my ears. 

Fried made a lot of models back in the day.

https://hifihaven.org/index.php?threads/fried-transmission-line-satellite-and-subwoofer-design.3638/page-2

I also had a pair of Fried transmission-line speakers. Can't remember which model, but if I recall, they has some kind of cross-connectivity like Polk SDA. I could be wrong about that. I didn't have them for very long, and it was probably about 20 years ago.