Considering that these are a niche product requiring a precisely shaped diamond insert made by a relatively small operation in the US, I think it's believable that a Chinese company could produce diamond files for ~$10, considering that it only needs diamond powder and has more space for mass production.
Considering that these are a niche product requiring a precisely shaped diamond insert made by a relatively small operation in the US, I think it's believable that a Chinese company could produce diamond files for ~$10, considering that it only needs diamond powder and has more space for mass production.