Machining marks and "China"
The "China" is a deep engraving that can't be buffed off as a previous reviewer said - it could potentially be ground out.
In addition mine came with deep scrapes and scratches around the hole from where the keychain was attached.
The quality of half of them is not suitable for selling in my opinion. A shame because if they hadn't been damaged in attaching the chain, and didn't have the mark they'd be a great size and weight. If you have the expertise and tools you may be able to finish them, but at least half are certainly not suitable as ready-to-stamp based on my batch.