This is definitely not an OEM quality piece of equipment. The fitment is pretty poor and the appearance is pretty tacky.
It will fall off every time you open the armrest up and is a little annoying to put back on. When you look at it through the windshield or side window, you can definitely tell it is an aftermarket cover, with a lot of overhang and excess material (particularly where the armrest curves like a "J" where your hand rests).
It is made out of a cheap vinyl, similar to the imitation leather on a cheap sofa.
However it does fit on the armrest and it works well to protect it. My 2019 Crosstrek has that little nick in it where they all wear, and this prevents me from causing further wear to it while shifting. For the price, I can't complain.