Windshield Antenna Kits

I notice that there is a Windshield antenna kit fir ICOM handheld radios.
According to a certain website...

" This antenna kit attaches to the inside of the windshield and dramatically
improves portable nav/com's transmit, receive, and
VOR performance based on extensive field testing. It is portable and ideal
for those who can't use an ANT-SB.
Simply attaches one's own flexible antenna to inside of windshield with BNC,
coax, suction cup adapter."


So my question is simple, why just ICOM radios ? Surely any handheld with a
BNC connector should be it ?

This is the site that I found it listed on...
http://www.aircraft-spruce.com/catal...antennakit.php

Rob.