Yes. Someone could still come steal my entire PC even with the case locked shut, but they can't easily pop open the side and pocket my ram! This is a simple, yet ingenious device. The bezel around the key hole spins freely so even if you can clamp a pair of pliers on the angled surface, it wouldn't loosen easily. A determined thief could unscrew this thing, but it will keep honest people honest. Very worth a few dollars for those of us whose self-purchased PCs are in a place with lots of other people around at all hours of the day and night.