Flipper

A flipper is a tab on the blade pivot used to open a pocketknife. The tab sticks out from the handle when the knife is closed; once opened, it also serves as a small crossguard. In order to open the pocketknife, the index finger presses down on the flipper, pushing the blade out of the handle. This opener requires smooth blade movements usually achieved with washers or ball bearings. With some models, you still need a flick of the wrist to fully open the knife.