I got these files as a sample in one of my boxes. I LOVE the convenience. The matchbox size and packaging is adorable and so handy to just throw in my bag.
The quality of these tiny files left something to be desired. They are definitely a one-time use and honestly were not very effective. They're very harsh.
I would most likely not buy the full-size product (though it may be more durable) because the convenience in size is what really sells this product for me.
Make the matchbox a product, not just a sample, and you'd have a buyer! :)