The AC21-N3W adapter package contains:
• the adapter - a metal ring for length extension
• the Z11 lockring - a longer lockring compared to the standard one that comes with the cassettes since it has to reach a deeper thread on the freehub after the ring installation. Lockrings that come with 10, 11 and 12 speed cassettes do not work when these cassettes are installed on N3W freehub + adapter as they won't SAFELY reach the internal thread of the freehub.
Hence, the full adapter kit comes ready to fit all our cassettes starting with 11 sprocket (11, 12 and also 10 speed). For those wanting to assemble a cassette starting with 12 sprocket we have a specific lockring available as spare part