It tops out at 1080p video (with HDR). The 4K-capable Chromecast is $50 (in Europe the prices are €40 and €70, respectively).
Google's more affordable Chromecast HD is available today for $30 - The Verge
Chromecast with Google TV - Google Store
Chromecast with Google TV review: A worthy rival to the best from Roku and Fire TV - CNET
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