N3W is a patented standard for a freewheel body engineered to house 11-, 12- and 13-speed cassettes with 9-, 10- and 11-tooth starting sprockets: NEXT 3 WAYS.
It is also still compatible with older 9- and 10-speed cassettes. N3W has the same groove profile as the classic Campagnolo body but it is 4.4 mm shorter, making it lighter. N3W is directly compatible with the new Campagnolo cassettes with 9- and 10-tooth starting sprockets.
To make it compatible with ALL of today’s cassettes with 11-tooth starting sprockets, simply use the N3W ring (kit ring + ring code AC21-N3W) which makes them the same length as the classic body.