If you're looking to turn your old TV into a smart TV, Amazon is running a cheap Roku promotion that you can't miss.

Right now, you can get the Roku Streaming Stick 4K for just $39. That's $20 off and the best price we've seen for this streamer since Thanksgiving.

The Editor's Choice Roku Streaming Stick 4K is one of the best streaming devices on the market, and our review of the Roku Streaming Stick Plus shows its simple, streamlined interface and HBO, Hulu, Netflix, Prime Video, and access to hundreds of other channels.

Most of the apps are too niche to be worth your time, but importantly, Roku has the widest variety of apps that you'll actually want to use compared to other streaming platforms. And unlike the Amazon Fire TV Stick, no one service is favored over the others.

In terms of performance, the Roku Streaming Stick 4K is more powerful than Roku's 1080p stick. During the test stream, content stabilized at 1080p within 5 seconds on a standard home Wi-Fi network, while it took about 10 to 15 seconds to reach 4K resolution on an office Wi-Fi network. Again, this may or may not be representative of what Roku can do in your home, but if your connection is up to the task of delivering 4K HDR content, so is the Streaming Stick Plus.