Very nice tool. Especially for curved surfaces.
I have a set of 4 and keep each loaded with a different grit.
The sanding strips are a bit expensive and clog pretty quickly.
You can find a package of sheets of "sandpaper" made of the same material as the strips.
I buy these, cut the strips, fold-glue the ends with super glue.
Making your own you can make them wider.
Its a bit time consuming buy will save a few bucks.
You can actually use any sandpaper and make your own strips.