Were trying to source ones with Black PCB's ideally but seems a very scarce market.
Ive seen a black one from ASUS. Think it was ROG branded.
While the adaptors are a good idea one issue that has been raised is that a lot of them don't allow Z87 motherboards to then use the Adapted M2 ssd as a boot drive. So while you get the blisteringly fast drive performance it cant act as an operating system drive.
This may not be true for all the adaptors / Z87 or older motherboards.