Nowadays the electronic gadgets such as smart phones, dash cam, GAPS, drone, Camera and tablets are in increasing demand for storage space, the minimum capacity they need is 16GB or 32GB at least, many users are still feel the space is limited. However, even they use these devices with 64GB embedded storage, the electronic gadgets is filled up with too many apps, videos, pictures or games. As they store more personal data or multimedia content, and barely do any deletion due to their rising demands. Moreover, some electronic gadgets don’t have spaces for extra data, the inside storage is just for loading its system files.

Therefore, when the storage space for electronic gadgets is shortage or nearly empty, among the various ways to enhance storage space, most people will choose to insert bulk micro SD cards or the other external storage to add the extra space, after all, this is one of the easiest ways.

Not all electronic gadgets s support micro SD cards, such as phone and IPA. However, many Android phones and tablets in the market support micro SD card as external storage, so does the Dash cam, Drone, GAPS and Raspberry pi and so on. These products are widely used in recent years.

If you expect to know whether the electronic gadgets support Micro SD card or not, the easier way is to check if the device equips with the Micro SD slot. Also we can check the manual book of them, it will give you clear guide. Usually the device manufacturers will do direct advertisement on that, as external storage is one popular option, they will do whatever to follow up users’ taste. There is one thing to remind smart phone users, although many android phones support Micro SD Card, they no longer provide separate position for loading it, the Micro SD slot is placing with SIM card to save spaces.

Now the urgent problem is how to choose a suitable micro SD card for our electronic products? At present, there are many kinds of micro SD cards in the market; they are in different prices, different capacities, different types and different brands. How can you truly choose one good Micro SD Card fit your own equipment or meet your personal needs? Let's firstly understand some parameters of Micro SD Cards as below.

The format of Micro SD Card

According to the data from SD Association, Micro SD Card is classified by the format of SD, SADHU and SAX. They are separately standing for Secure Digital, Secure Digital High Capacity and Secure Digital Extended Capacity; the difference among them is mainly capacity and speed.

SD version is the earliest one, the capacity of this format starts from wholesale Micro SD Card 128MB to 2GB, and the speed is the lowest one. The upgrade version of SD is SADHU, the capacity gets rising from 2GB to 32GB, and it is also the common one in market. The last one is the SAX; all high capacity will follow this format from 32GB to 2TB, so far the max capacity available in market is 1TB, the cost of it is almost same as one smart phone.

The speed standard of Micro SD Card

We will firstly introduce two main speed standards of Micro SD Card defined by the SD Association; there are Class level and HUS level. Class refers to the minimum transmission speed of the card. For example, Class 4 stands for 4MB/s by write and Class 6 stands for 6MB/s by write. So the number indicates the writing speed, it will be easily identified.

HUS means "ultra-high speed (Ultra High Speed)," and "HUS speed level" defines Micro SD cards by the lowest write speed, such as US-I speed level 1, which has the lowest 10MB/s by write. US-I speed level 3 (US-3) has the lowest 30MB/s by write.

The following introduction is the reading speed for the different speed levels of the micro SD card.

It is important to note that the marked speed of most micro SD cards is much faster than the minimum one, for example, the micro SD card identified by Class 10 can provide 95MB/s for reading, while US-rated cards can be as fast as 312MB/s by read.

In addition, there is no corresponding relationship between the speed level and the HUS speed level. However, in terms of speed, the Class 2, Class 4, and Class 6 speed levels are just normal speeds, with Class 2 suitable for low-resolution video, while Class 4 and Class 6 are suitable for high-definition or 1080p full-HUD video. The Class 10 is faster than the previous ones and is suitable for 1080p full HUD recording or continuous shooting of high-definition still pictures.

As for the HUS speed level, the highest HUS-I speed level 1 can meet the 1080p full HUD recording or continuous shooting of high-definition still pictures, and the US-3 can meet the 2K or 4K resolution video recording.

App Performance Class

At the end of year 2016, the SD Card Association also introduced one new standard called "Application performance level (App Performance Class)", it mainly to highlight the use of micro SD cards for mobile devices such as smart phones or tablets, and ensure that applications are run with optimal performance to meet the technical market needs of mobile devices. As a result, such micro SD can not only store pictures, movies, music, files, and other data, but also be able to run and store applications.

The most basic application performance level is: App Performance Class1, or A1 for short. Micro SD cards marked with A1 symbols must meet or exceed the following performance under certain conditions:

• Random Read: 1500 (IO PS)

• Random Write: 500 (IO PS)

• Sustained Sequential Write: 10MB/S

Micro SD cards marked with A2 symbols must meet or exceed the following performance under certain conditions:

• Random Read: 4000 (IO-PS)

• Random Write: 2000 (IO PS)

• Sustained Sequential Write: 10MB/S

No matter the Micro SD Card is with A1 or A2, it is basically fast enough to open applications or process tasks in the device. Furthermore, micro SD cards have been supported as "suitable storage (Adoptable Storage)" since Android6.0 Marshmallow; it is being used as built-in storage.

The Final decision of purchasing Micro SD Card

Obviously, everyone wants the fastest, highest capacity, and lowest price micro SD card. In fact, there are many brands in the market, such as Sam sung, San Disk, Toshiba, Kingston and the other wholesale Micro SD Sources, and so on. As we have introduced the parameters of the micro SD card above, I believe it is no longer a problem for selecting cards on your own.

For example, one micro SD card labeled Class10 or HUS-1, and providing a maximum 80MB/s speed can support basic 1080p video recording. Memory cards labeled SAX, HUS-II, or 100MB/s are suitable for 4K video recording.

In fact, there are a lot of micro SD cards marked with A1 symbols in the market, the price is relatively expensive, e.g. the 32GB is around $9/PC, the cheapest 128GB GB is around $23/PC. You should give priority to such micro SD cards if you need A1 performance, it will ensure that the mobile performance going smooth.

In addition, the purchase of micro SD cards must be related to brand reputation and user comments, as one good Micro SD supplier can guarantee the quality, speed and warrant; and the reviews of user will tell you the actual using experience.