Garmin maps are available in a variety of formats. They may be purchased on DVD/CD ROM, on a pre-programmed µSD card, or downloaded directly from the Garmin website. Many excellent non Garmin maps are also available online from multiple sources. Pre-programmed µSD cards are ready to use immediately out of the box. Simply unpack the card and insert into your compatible GPSr device. These maps do not need to be unlocked to your device which allows you to move the card between multiple units as desired. BaseCamp can be used to view mapping detail on your computer from compatible pre-programmed µSD cards. Mapping data from the µSD card cannot be copied. Maps purchased in this format will require a computer to use. The installation process will install the maps and BaseCamp application to your computer. BaseCamp can then be used to send maps to either your device or µSD card. Please note that most mapping products in this format are unlocked to a single device and they are non-transferable. Maps purchased in this format can be downloaded directly from the Garmin website. Downloaded maps can be sent to either your GPSr unit or µSD card. All maps in this format are unlocked to a specific device and they can only be used on the device that they were unlocked to. BaseCamp can be used to view downloaded mapping detail on your computer. Not all maps require installation to a host computer to be available in BaseCamp. Maps in the following formats can be copied directly to a GPSr, µSD card, USB Drive (Virtual GPSr) or other removable media as shown: If the downloaded map file is not in *.gmapi format, double click the file to launch your default archive utility and extract the map from the compressed archive If the Garmin Communicator Plugin is not installed on your computer, follow the instructions on the Unlock Maps page to install the Garmin Communicator Plugin. Newer map products may have additional requirements for unlocking. Follow the unlocking instructions included with your map product. Do you have a paper map you want to use with your Garmin GPSr? Perhaps you have downloaded a local or state park map in PDF format and wish you could somehow get it into your Garmin GPSr? Convert Annual subscription based service providing unlimited access to Garmin satellite imagery and/or detailed USGS/NRC topographic raster maps for use with your Garmin GPSr and BaseCamp. Allows you to layer the Garmin vector maps on your handheld (such as TOPO 100K, TOPO 24K or City Navigator®) with BirdsEye Satellite Imagery for a real-life view of roads, buildings and terrain. Allows travelers to view tourist hot spots and landmarks from an aerial view to make excursions memorable without getting lost Layer Garmin vector maps (TOPO 100K, TOPO 24K, City Navigator) on your Garmin GPSr for a ‘birds eye’ view of roads, buildings and terrain. Each single purchase allows you to select and purchase custom sections (a set amount of square kilometers per region) of BirdsEye Select raster imagery for transfer to your Garmin handheld device. Not all maps are created equal, and no one map should be considered inferior or superior to another map based solely on price. In fact, some of the most useful maps you are likely to use with your Garmin GPSr are freely available from numerous map hosting websites. When you find a free map you like, consider making a donation to the map author to motivate them to continue the development of their maps for your benefit and enjoyment! (USA) A compendium of over 35,000 trails ranging from National Parks and Forests to local, backyard mountain bike trails. Source.