Folding knives of the double action type in which a pivoted blade can be moved from the sheathed position within the handle and lock automatically in the unsheathed use position in two different ways at the option of the user, namely, (a) to snap the blade into the use position via spring action by movement of a release trigger or (b) to silently unfold the blade manually into the use position, are improved by providing the knives with hidden release triggers, i.e., triggers that are not…