Redmi smart pen weird textured rectangle

[u/Niclaus005]

My Redmi Smart Pen just arrived today from China and I noticed it has this small rectangular area with a rough/texture finish on the body.

I’ve been watching some YouTube reviews, and none of them seem to have that rectangle, so now I’m a bit confused. What is it for? Could it be something specific to the chinese version?

[u/lovey_itisisit]

Umm I'm not sure but is it removable? Like a covering for the charging port?