This RTL SDR dongle uses the R820T2 chipset and can be used on frequencies from 25MHz to around 1800MHz. It allows reception of AM, CW, FM, SSB for Amateur Radio as well as airband, broadcast radio and other frequencies (incl plane-radar/tracking). Subject to software and computer power, your waterfall can span over 2.5MHz and you can decode a variety of digital transmissions (DMR, Pagers etc) with suitable software (we use HDSDR in our Shack).
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These were designed for receiving DAB/Freeview broadcasts (typicall in high-signal areas) but make great add-ons to a Ham Shack. A small magmount aerial is provided (which is suitable for mounting near a window to track aircraft) but, for best results, you are advised to use an aerial tuned for the operating frequency - for that, you have the option to include a BNC or SO239 adapter as part of the package.
Newer (and more expensive) versions of the RTL are able to directly sample HF without any modification - be wary of imitations and poor sensitivity/selectivity of some versions! More expensive SDR units have bandpass filters making them better for more critical applications.
Compatible with software such as HD-SDR and SDR# (now Airspy SDR#). Read this article for a comparison between this and the original R820T dongle. These also work on the Raspberry Pi - check out this page for details of rolling your own Pi-based SDR receiver!
If you're looking at tracking planes, Dave M0TAZ has written a useful blog post on ADS-B reception here.