6” Shove Knife by FireHooks Unlimited:
Versatile, little tool is often the quickest, easiest, and least destructive way to spring the latch on interior doors in residences or offices with simple “key in knob” locks.
The clever design lets you use the knife from either side of the door. If the door opens inward, you shove the thin, flexible “blade” knife in back of the molding stop and push or slide the blade to retract the latch. For doors that open towards you, the knife is slipped in from above or below the latch point and jiggled and pulled to hook and retract the latch.
A two-piece protective sleeve covers the “blade” when the tool is not in use. Used extensively in fire towers to slip spring latch locks.