The SecureLok works off of the blade itself, instead of off the liner as with the InterLock safety. After the blade of the C25 or C50 Centofante models is opened and the SecureLok is engaged, the safety acts as a second lock, wedging the blade in the open position. Therefore, lock failure is averted.
With the Interlock, it wedges underneath the liner lock bar, preventing it from being depressed. I haven't seen how the newer Interlocks work, but I have a sample from the first production run of the Coverts where the safety was that sliding button mounted in the scale opposite the clip. Hope this helps.
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Dexter Ewing
Knife Reviews Moderator
"The keystroke is mightier than the sword"