Regular Tuned Duck show a 3db minimum gain over other rubberducks because they are impedance matched to a hand-held radio. They are available in MPQ-2000 Space Age covering system. This new flex coil matching network provides at band center low SWR as well as a +or - 5 MHz band center. (Example an antenna tuned at 146 being the band center, the antenna will perform the same between 141-151 MHz.) For custom frequency call 1-800-527-5439 or email sales@smileyantenna.com. 7 1/2"