I own 4 of these, I have used them for a few years now.
I have literally caused structural damage with 4 of these in a club 2 each side. They are definitely the number one active double 18" bass bin for the money and I haven't seen or heard anything come close for the price.
I own 8 of the Achat 118a horns but they have a totally different sound to these playing better in bigger venues and outside. These in a medium sized room are extremely effective and you don't have to pair them up or play them in groups like a horn box.
For a larger room you will need more then a pair as they have a weird cut out feature when they clip, the Achat or single TP118a boxes don't have this feature but judging by the size of the amp on this box I can see why, its almost double the size! It is a good safety feature to have but I find sometimes they clip and the bass goes for a bit too long while the Achat or single TP keep going. Sometimes just as the bass gets to a sweet spot the limiter will kick in and the box goes into limit mode for a few seconds. With the other boxes you can hear when they clip and know to back off the bass a bit but these boxes just cut themselves off.
This feature can be good if you leave your sound unattended but I would rather set limiters myself on my speaker management system or Digital mixer. If I know a venue is big I always carry 4 or just bring my horns instead.
These boxes have the best handles out of all of the box pro range. Lots of steel bar handles so they are easy to carry and move about with another person.
A very good box, These must be the most sold Box Pro active speaker as everybody has them now. They are definitely an impressive box but don't push them too hard or go too crazy, add more so they can play more easily, comfortably and avoid clipping.