The backlock, as seen in the Buck 110 Lockback knife is a classic locking knife system. It is one of the few styles of knife locks that are considered traditional, in its pure form.Backlock knives have a notch at the pivot end of the blade where a lockbar hooks in, securing the knife in its open position. The lockbar stays in place with the use of a spring. To close the knife a mechanism lifts the lock back out of the notch so the knife can close. There are several variations on how the lockbar is lifted and how big it is but the basic system is the same.The notch and the lockbar are the tell tale signs of a backlock.Here you can see it more clearly. (Thanks for the GAW, again)(Image removed from quote.)(Image removed from quote.)The classic lockbacks with backlocks have a long lockbar, with a pivot near the middle of the knife, which makes it easier to open (better leverage).(Image removed from quote.)See the length of the lockbar.(Image removed from quote.)(Image removed from quote.)The most common variation is the midblock, where the lockbar is shortened and the and release button are moved forward. This makes it harder to unlock the blade and is supposed to provide a stronger lock.(Image removed from quote.)Shorter lockbar.(Image removed from quote.)(Image removed from quote.)Some not so obvious lockbacks or variations are shown here. I must point out that some may not consider these true backlocks, but they use the same basic principle for locking.The GEC variation uses a lever to lift the lockbar (bull lock according to GEC and it does not pivot; you just lift one end up). The notch has two steps in it.The Mercator has a protruding area where you push down to release the lock.The Manly uses a lever that releases the lockbar totally (removes the “spring”) so the knife can close freely.The Wenger uses a button to push the lock up, from the bottom side.The last one, from LIDL, is unusual in that it locks both open and close and you need to push the lockbar button to open or close it. (Image removed from quote.)(Image removed from quote.)(Image removed from quote.)(Image removed from quote.)Finally, showing that classic designs continue improving we have the Tri-Ad lock, that is an improved backlock system, designed by A. Demko and known for being really strong, and not so easy to release. Here it is used on the CS Spartan.(Image removed from quote.)(Image removed from quote.)Finaly, backlocks have been used in multitools too.Enjoy.