Samsung Note 10 with microSD memory cardSource: Ara Wagoner / Android Central

This Black Friday you'll find plenty of SD cards on sale at great prices. I've picked up a couple of these SanDisk Extreme cards myself because the price was right. One other thing about them is right, too: the card speed.

You'll see a lot of reasons why a faster card is better. Most of them delve into the read and write speeds and talk about how fast you can copy files to and from the card. This is important, but it's not the real reason why you want the fastest card you can afford for your phone or anything else with a camera. The real reason is short and sweet — 4K video.

Read and write speeds vary based on card class. You'll see things like Class 10, or U1 labeled on a card and that designation is all about the reading and writing speeds the card can maintain. These numbers are all listed and tested under absolutely ideal conditions and you'll never achieve them, but higher-rated cards are faster in every type of use case.

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Sandisk Sdxc Render

Need for Speed: SanDisk Extreme 128GB microSD card

You need a fast SD card to transfer files at high speeds and to shoot crystal clear 4K video. These SanDisk Extreme cards are time-tested and plenty fast enough. Grab one or more while the price is right!

$20 at Amazon

One of those use cases is when you're taking video with your phone or anything with a camera like a drone or even a security camera. Simply put, if you want to take 4K video that looks great you want to spend a few more dollars and buy a card that's rated U3 like the SanDisk Extreme cards.

The brand can matter, too, especially when it comes to longevity or the chance of getting a "fake" card that is labeled with a higher capacity or speed than it actually is, but a card that actually is rated as a U3 speed card will be about the same speed no matter which company makes it. If it's a reputable company, you'll be fine.

When you fire up your camera to take a video you're grabbing what you see, transforming it into a digital file that's streamed to your SD card. While it's streaming it's continuously writing data to the card just as if you were transferring a large file. Being able to write 4K video at high speed is important.

Galaxy Note 10 camera uiSource: Android Central

A slower card will probably work, but might not necessarily work well. If you can't write the video file to the card fast enough, your video will suffer. You'll see blotchy colors, bad motion blur, or fuzzy video. Maybe even a combination of all three. Think about trying to watch a 4K video over a bad connection and how that can affect how the video looks on your screen. Writing while using a "bad" connection — in this case, the storage being the bottleneck — does the same thing.

Yes, you can save some money buying a slower card. If you aren't planning on taking 4K video, you can get away with a slower card and save some cash, which is always a good thing. But if you plan to take advantage of the great 4K camera on your phone and store the videos on a micro SD card, you'll be a lot happier if you spend the extra cash and buy the highest rated card you can.

Samsung Evo 256GB U3 MicroSD Memory Card

Samsung EVO Select 256GB microSD card

Samsung's Evo Select line is the most popular and well-trusted microSD card series, and it will double or quintuple the storage in most phone and Chromebooks for less than the cost of pizza night for the family.

$25 at Amazon
SanDisk 512GB Nintendo Switch MicroSDXC Memory Card

SanDisk 512GB Nintendo Switch MicroSDXC Memory Card

This particular MicroSD card is officially licensed for the Nintendo Switch, and it offers transfers of up to 100MB/s. With 512GB of storage, you have enough room to install all of your favorite games, and the card comes with a lifetime warranty.

$80 at Amazon

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