I would not recommend this type of ADS-B. This USB Stick ADS-B devices are only for the Tis-B or Traffic, which is extremely limited at this time. As we get closer to 2020 and more aircraft are ADS-B out equipped, then it might be something to look at. This GNS unit will not provide any FIS-B or NexRad, Weather and Flight Information.
The US uses 2 bands for traffic, the 978 and 1090 as the prior post notes. Having 978 only, provided it is compatible with the US network, I'm guessing so, would have very little benefit. ADS-B traffic is best when used with a In/Out Transceiver. Hope this helps clear things up. Be aware of these USB ADS-B devices as the US only support the FIS-B or Weather, other countries only use it for Traffic.