These antennas rapidly pick up your position.  It can be placed on the roof of the car or mounted internally on the windshield using one of our antenna mounts (which I like a lot).  The base of the antenna is magnetic so it will adhere to any metal surface.  These are simple to attach to your GPS.  Just plug it in and you're done!

The antenna itself is the size of a US half dollar and the cable is 15 feet long.  This is very comparable to Garmin's External Antenna (Garmin 25C) and less than half the price too.  

Fits many models including:
AT&T Cisco 3G MicroCell
Garmin Nuvi 885T 880 860 855 850 780 770 760 750 710 700 680 670 660 610 370 360 350 310 300
Garmin Colorado 300 400i 400t
Garmin eMap
Garmin iQue 3600 3200 M5 M3
Garmin Montana 600 650 650t
Garmin Streetpilot 7500 7200 2820 2730 2720 2710 2650 2620 2610 C580 C550 C530 C340 C330 C320 C310 i5 i3 i2
Garmin Zumo 550 500 450
Garmin Quest 1 or 2
Garmin GPSMAP 60 60c 60csx 60cs 60cx 72 76 76c 76s 76csx 76cs 76cx 78 78s 78sc 175 195
FineDrive 500 400 300
TOMTOM GO 930 920 910 730 720 710 630 530 520 510 ONE XL