For the Bluebird chain, Odyssey took the proven and reliable KMC 510-HX chain and added a permanently attached, factory installed half-link to one end. When the chain is trimmed to size you can easily decide whether or not to use the half-link.
Original factory assembled pin joints are radically stronger than workshop assembled half-links.
Proven and reliable KMC 510-HX chain
Factory installed half-link on one end for a radically stronger set-up