It's what you say, a loudspeaker (a 'tweeter') with a 'Kalotte' in the center of it (to direct/reflect the sound):

http://images.google.de/images?hl=de&q=kalott... . . .

Dictionary: Kalotte+Hochtöner . . .

dome loudspeaker
dome midrange speaker

... and as your flyer is on woofers, it will be a 'Kalottenhochtöner', mounted in the center of a woofer, in front of it's membrane . . .

woofer [tech.] = der Tieftöner
woofer [tech.] = der Tieftonlautsprecher . . .

Thanks a bunch...the full word is aluminumkalottenhochtöner.

aluminum dome tweeter

@ #4: You are obviously translating into AE, ain't you ? . . . ;-)

The German word will have read: 'Aluminiumkalottenhochtöner' [je 2 'm', 'u', 'i' in Aluminium] . . . ;-))