With most new GPS devices it has become less important to have an external antenna jack since the most newer chips are sensitive enough to acquire an adequate signal inside a vehicle or boat. However, it is not always possible to obtain good satellite coverage through a front windshield as sometimes the GPS receiver cannot or will not be placed near a window. This is when an external GPS antenna can help. Even backpackers will benefit from the ability to safely store the receiver inside a pack with an antenna attached to your backpack shoulder straps. It can also help outdoor use in places in like heavy tree cover, mountains or in canyons where signals are weak. Also, tall buildings in cities can create “urban canyons”, or in any place that the receiver doesn't have a good view of the sky you will want to minimize temporary loss of signal when you are in motion to maintain the best possible accuracy by having a lock on the greatest number of satellites.