I bought 4 of these about 2 weeks ago to install in the ceiling for my home theater for the .4 in a 7.2.4 home theater build.  It took me a while to figure out how the plunger screw thing worked  - I thought I was doing something wrong.  But you have to turn left, then right and plunger will easily tighten down.  I didn't know this and was applying the force of superman to crank down the plunger.  After about the 3rd install I realized the trick.  2 were installed in a drop ceiling and the other 2 where installed in a drywall ceiling.  Templates provided made for easy cutting of holes.  The sound from them is just simply amazing and work really well with the rest of my NHT setup.  I was amazed at how big they are.  I'll post some pictures shortly of the install - but here are some of the speaker itself.