Does anyone know what is this?

[pedro.dantas]

I've seen a lot of people using it to put the rubber on while boosting.

 

[dingyibvs]

It's just a sewing mat, kinda like this one

https://a.co/d/eZpQ7dD

 

[lodro]

Not a sewing mat but a cutting map. After you cut your rubbers on it the cuts on the mat will heal themselves. Good thing to have

 

[plunder]

mine is A1