Lexar Dual Drive D40E 128GB USB flash drive
Here you will find a detailed speed, performance and benchmark test review. Tested was the USB flash drive Dual Drive D40E with 128GB (LJDD40E128G-BNSNG) from the brand Lexar.
| Technical specifications (manufacturer information) | |
| Product image | 
|
| Manufacturer | Lexar |
| Model number | LJDD40E128G-BNSNG |
| Capacity | 128 GB (116 GiB) |
| Read speed | 100 MB/s |
| Write speed | no information |
| Interface | USB 3.2 Gen 1x1 (5 Gbit/s) |
| Connector | USB Typ A+C |
| Controller | n/a |
Compare product Compared to the test winner*
We put the 128 GB Lexar USB flash drive through a detailed test. You can find the test result / test report here:
AS SSD Benchmark
Standard performance test
The standard test was performed with a 1 GB file. A total score of 50 points was achieved.
Copy performance test
A common everyday scenario is simulated here. Three test folders are created:
- ISO (folder with two large files)
- Program (folder with many small files)
- Game (folder with small and large files)
The three folders are copied using the Windows copy command (cache remains enabled). The real-world test from 31 March 2025 shows performance during simultaneous write and read operations. The lower the duration, the better.
| AS SSD Copy Benchmark | Transfer rate: | Duration: |
|---|---|---|
| ISO two large files |
44.95 MB/s |
23.89 s |
| Program typical program folder with many small files |
15.44 MB/s |
91.15 s |
| Game a game folder with small and large files |
27.30 MB/s |
50.60 s |
Compression performance test
Here, speed is measured depending on how compressible the data is.
CrystalDiskMark Benchmark
Similar to AS SSD, two sequential and two random performance tests are carried out here and the write and read speed (manufacturer specs: 100 MB/s) the Lexar USB flash drive is measured.
| CDM | Read [MB/s] | Write [MB/s] |
|---|---|---|
| SEQ1M Q8T1 |
183.20 |
94.73 |
| SEQ1M Q1T1 |
204.84 |
94.81 |
| RND4K Q32T16 |
14.13 |
1.32 |
| RND4K Q1T1 |
11.67 |
1.43 |
IOPS (Input/Output operations per second)
| CDM | Read [IOPS] | Write [IOPS] |
|---|---|---|
| SEQ1M Q8T1 |
174.70 |
90.30 |
| SEQ1M Q1T1 |
195.30 |
90.40 |
| RND4K Q32T16 |
3,449.50 |
321.30 |
| RND4K Q1T1 |
2,849.40 |
348.40 |
Average latency
| CDM | Read [µs] | Write [µs] |
|---|---|---|
| SEQ1M Q8T1 |
45,522.70 |
87,592.50 |
| SEQ1M Q1T1 |
5,114.60 |
11,041.50 |
| RND4K Q32T16 |
105,902.00 |
352,234.00 |
| RND4K Q1T1 |
350.72 |
2,845.88 |
HD Tune Pro long-term test
A long-term test was performed to fully utilize the storage. You can see at what point the cache (if present) becomes full and write performance drops. A test file of 4 GB was written to the medium.
HD Tune Pro Benchmark
HD Tune writes a 1 GB file to the 128 GB Lexar USB flash drive. The transfer data of the read speed is displayed graphically. The minimum, maximum and average values are also determined. The measured access time and burst rate are also shown.
ATTO Disk Benchmark
Here, a 256 MB file is written to the 128 GB Lexar USB flash drive multiple times. The I/O block size varies (from 512 bytes to 64 megabytes). The larger the blocks, the faster writing and reading usually becomes.
SSD-Z Benchmark
Similar to HD Tune, a 500 MB file is written to the 128 GB Lexar USB flash drive here. The transfer data is displayed. The more consistent the line, the better. Unfortunately, the tool no longer works correctly from around 4,000 MB/s and no line is displayed (and sometimes incorrect min/max data is shown).
You can find information about the test system at the bottom of the homepage.
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