Boston Acoustics RALLY RM9 - Manual (Page 9)

9
RM9 Installation Option
The RM9 can also be installed from underneath the rear deck to reduce
the installed height of the tweeter module. A spacer is supplied to pro-
tect the rubber surround and ensure a tight air seal. The spacer is
installed between the speaker and the mounting surface as shown in the
diagram.
The Kortec™ dome tweeter on the RM9 is asymetrically aligned with the
woofer cone to minimize diffraction of high-frequencies off of the cone.
Although they are packaged in stereo, matched pairs, either speaker may
be mounted on either side of the vehicle.