You may buy it by this affiliate link on aliexpress store.
http://oss.digirati.com.br/f3/
f3 - Fight Flash Fraud
f3 is a simple tool that tests flash cards capacity and performance to see if they live up to claimed specifications.
F3 stands for Fight Flash Fraud, or Fight Fake Flash.
# Raspbian lite was installed and partition was enlarged in raspi-config.
$ sudo f3write /media/microdata-32gb-sd-card/
F3 write 7.1
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.
Free space: 26.70 GB
Creating file 1.h2w ... OK!
# ...
Creating file 27.h2w ... OK!
Free space: 16.00 MB
Average writing speed: 5.03 MB/s
$ sudo f3read /media/microdata-32gb-sd-card/
F3 read 7.1
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.
SECTORS ok/corrupted/changed/overwritten
Validating file 1.h2w ... 10996110232097152/ 0/ 0/ 0
# ...
Validating file 26.h2w ... 2097152/ 0/ 0/ 0
Validating file 27.h2w ... 1427616/ 0/ 0/ 0
Data OK: 26.68 GB (55953568 sectors)
Data LOST: 0.00 Byte (0 sectors)
Corrupted: 0.00 Byte (0 sectors)
Slightly changed: 0.00 Byte (0 sectors)
Overwritten: 0.00 Byte (0 sectors)
Average reading speed: 6.26 MB/s
$ sudo f3probe --destructive --time-ops /dev/sdb
F3 probe 7.1
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.
WARNING: Probing normally takes from a few seconds to 15 minutes, but
it can take longer. Please be patient.
Good news: The device `/dev/sdb' is the real thing
Device geometry:
*Usable* size: 29.16 GB (61157376 blocks)
Announced size: 29.16 GB (61157376 blocks)
Module: 32.00 GB (2^35 Bytes)
Approximate cache size: 0.00 Byte (0 blocks), need-reset=no
Physical block size: 512.00 Byte (2^9 Bytes)
Probe time: 10'13"
Operation: total time / count = avg time
Read: 1.11s / 4815 = 231us
Write: 10'11" / 4192321 = 145us
Reset: 3us / 1 = 3us