Genuine ABUS key blank 6N.
Suits code series 6N0001 - 6N9999, 00016N - 99996N, 8N0001 - 8N9999 and 00018N - 99998N.
This type of key is common in padlocks and bike locks, especially ABUS Ultra 410 locks.
The key needs to be both cut and milled.
Cut key shown in second image.