It uses Dahon's "Lockjaw" design. The top and down tubes are split/hinged and have an aggressive locking "tooth" design. Everything is secured/loosened with an allen key.
Pics and review:
Dahon Cadenza
Also a very nice ride:
2011 Cadenza
Last edited by El Duderino X; 04-23-11 at 05:39 PM.