The manual says:

1. Turn the speaker till the tweeter slots look horizontal when viewed from seating position.
2. Press the tweeter edge to aim it towards the listener.

I did the first part. However, I found that the tweeter cannot be now aimed. It can only be aimed along the slots, not perpendicular to the slots. Why is it designed like this? I think it is important the tweeter be aimed towards the listening position. So I rotated the tweeter so that when I look at it, I see the slots vertically. And now I can aim it towards the listening position, and the sound is great.

Any thoughts on this?

The engineers tried to provide enough flexibility for typical, but not all, installation locations. The tweeter is slightly broader in dispersion in one plane, so we suggest orienting it accordingly (slots horizontal). We also suggest aiming the tweeter towards the center listening position (or for surrounds/rears, towards the corners if a more diffuse sound is wanted). Neither is critical and if only one is possible in your setup the results will still be excellent - as you've discovered. Enjoy!

Do we know what is maximium angle you can pivot Invisa 5 tweeters?