I first noticed PreSonus' Eris monitors two or three years ago when their E5 and E8 models forced their way into the already crowded affordable-studio-monitor market. They seemed to get pretty good reviews, and I figure they've probably sold well since. At the time the E5 was the smaller of the two options (E8 being the other) and I was interested to see that the range has expanded smaller (chaos creeping in? - Ed) to the E4.5.
The E4.5 is a compact and lightweight speaker and has a quite-different look to its bigger range-mates. Cabinets are MDF with 4.5'