
Lexar High-Performance 633x 256GB
Score: 60/100
Transcend 128GB Micro SD Card
Score: 82/100Rankings

The Transcend 128 GB microSDXC card offers high endurance and fast read speeds, making it ideal for dashcams and continuous Full HD recording. Its write speed falls short of U3/V30 standards, limiting 4K performance. Best suited for users needing rugged, long-life storage in harsh environments.

Lexar's 256 GB 633x microSDXC offers up to 100 MB/s read speed, a V30 rating, and includes a micro-SD to SD adapter for versatile use. Its slower 45 MB/s write speed and lack of waterproofing limit high-end video applications. Suitable for smartphones, tablets and action cameras where large capacity and broad compatibility are priorities.
| Attribute | ![]() | ![]() |
|---|---|---|
256 GBbest | 128 GB | |
100 MB/sbest | 100 MB/sbest | |
45 MB/s | 85 MB/sbest | |
| ↓ lower better | 453.6 g | 0.4 gbest |
— | 5 yearsbest | |
| ↓ lower better | 1.02 mm | 1 mmbest |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | ![]() | ![]() |
|---|---|---|
Storage(1) | ||
Capacity (GB) | 256 GB | 128 GB |
Performance(3) | ||
Write Speed (MB/s) | 45 MB/s | 85 MB/s |
Speed Class | C10 | U1 |
UHS Speed Class | U3 | UHS-I |
Design(2) | ||
Weight (g) | 453.6 g | 0.4 g |
Thickness (mm) | 1.02 mm | 1 mm |

Products in the top-left offer the best value (high score, low price).

Professional testing shows the Lexar 633x card delivers real-world read speeds near 97 MB/s and write speeds around 69 MB/s, surpassing its advertised specifications and confirming its suitability for 4K video capture. Reviewers acknowledge its solid mid-range performance but point out that newer Lexar BLUE models provide higher peak speeds, making the 633x less compelling for users seeking top-tier throughput.
Everyday users praise the large 256 GB capacity, the included SD adapter for easy file transfer, and the peace of mind from the lifetime warranty. They also highlight the card's reliable 4K video performance and compatibility with a wide range of devices. However, some users note the write speed feels modest compared to newer offerings, and the lack of UHS-II support limits its appeal for high-end professional use.

“built to last”

“decent 40ish MB/s write speed”




Professional reviewers and editors consistently commend the Transcend 128 GB endurance card for its rugged build, extreme temperature tolerance, and impressive 30,000-hour video endurance, noting that its 100 MB/s read and ~45 MB/s write speeds are adequate for continuous Full HD dashcam and security-camera workloads.
Everyday customers echo the professional praise, highlighting the card's durability in dashcams and security cameras and its ability to record long stretches of Full HD video without failure.