This knife does not have a lock but is held open and closed by adjusting the tension on the thrust washers to desired tension. It comes pretty loose from the factory and is easily adjusted with a flat head screwdriver. The Prawn is a great piece for your backpack or EDC as its compact size makes it easy to carry and its quickly deployed and closed blade is a feature we absolutely love. The stop pin works in both directions and keeps the knife blade in place whether it is open