Designed by Ken Onion, so it features his Speed-safe AO. Also features his "Vault Lock." I contacted him about it on Facebook and he told me that after Kershaw produced the first limited edition/numbered run, they decided it was too expensive to produce and cancelled it. As a result there have only been 250 made. I bought it recently right here on the forum.
The knife is interesting. Construction-wise it's the mixed bag that you would expect from a limited edition Kershaw -- really nice 440V(S60V) blade steel and titanium frames with what appears to be some absolutely cheapo thermoplastic bits. Appears to have bronze washers.
The lock is REALLY interesting. It's pretty clear that at some point, Onion was interested in integrating the thumb stud into the locking mechanism. He did it, for example, on the Kershaw Speed Bump. This is the better design, IMHO. The blade locks between a stop pin (blue arrow) preventing positive (opening) pressure and the thumb stud (red arrow) preventing negative (closing) pressure. Despite how it looks in the picture, the thumb stud doesn't work against the frame. To unlock, you pull back on the mechanism in the direction of the green arrow. It is spring loaded and slides in a slot in the frame. In principle, it's like a bolt lock that acts against the thumb stud instead of the tang. The details of construction are, of course, really different between the two locks. Locks up solid with no detectable blade play.
Pictured is #247, stolen from the internet. I own #248.