Exactly what I was looking for
The backup fits in your pocket. Dimensions 65 x 50 x 10 mm, less bulky than the plip in my car!
Heats up to +11°C above the office environment after 1 hour of continuous writing. The heat control on this product is remarkable.
Speed: 1050Mb/s announced on the Crucial website, obtained by internal testing (they're the ones saying it).
My backup: 500Mib archive files, writing is maintained at 210Mb/s, which isn't too bad for a gizmo that doesn't get very hot. For 4kib to 50Mib files, it's slower: 50Mb/s to 80Mb/s. Once loaded, my backups are limited to files modified during the day, so the day's backup rarely lasts more than a minute (including mounting and dismounting). Totally efficiently managed by Linux Mint 21.0.
One last detail: the little hole for hanging the ssd has an LED to indicate that it's working, a diffuse white LED that doesn't dazzle, thanks to our eyes.
For me, it's the ideal product for carrying my data around in my pockets.
Summary: I'm happy, very happy.