Really cheap but I have it in my apron pocket all the time and use it all the time.
It is a 1 3/4 x 1/4 x 8 inches pine strip, it is covered with 3M P400 sticky back sand paper, left over form a auto body project.
I use it all the time, it takes off that little fur that is on the edge of a cut. It doesn't really hurt the edge just take off the very fine stuff that the blade leaves and I am using a Forest blade.