I needed such a tool to level the frets on necks for my guitars. I normally use a plastic card, but a metal piece is better for the purpose because it vibrates louder and it holds shape better.
This tool is cut appropriately to use it on all fret distances, from the highest guitar frets to the lowest on a bass guitar, normal scale length, at least.
The problem is the edges of this piece or metal are cut rough and scratchy, not filed at all, let alone straight. Its points are bent and sharp, straight out of the CNC machine. This is unacceptable to a dedicated tool, on which someone relies to have their guitar frets leveled.
Concluding, this product is just a rought piece of metal, useless out of the box. It can be useful if one files its edges straight and smooth.