This is one of the original 15s that were made before Andrew's AD10 and AD15 Cold Steel-made production knives. It's a full thickness, hand-ground Andrew Demko custom AD15.
The Scorpion Lock is a one hand operable backlock and is the strongest lock Demko has made. It is a Tri-Ad lock that also gets stronger with hand pressure on the handle.
Fit and finish is perfect. Hinderer XM-18 3.5 and Strider Knives SMF only shown for size comparison.