I recently bought a 1.5 million volt rechargeable stun gun and a police grade can of pepper spray for one of my daughters who is going away to school in the Fall. They are the size of and smaller than a cell phone respectively. The loud “pop” the SG makes when discharged would give anybody pause. But even a hat pin and a whistle would be better than nothing.
The loud “pop” a 1911 .45 makes when discharged is much more effective at giving pausing to as assailant.