Item is effective, if you can remember where you left it and you can get to it in a hurry. One hard torso strike would slow down any assailant without gun or knife. On a lanyard tight to the wrist under your sleeve, this could drop down into your palm quickly and stealthily. My own sense of self-defense is that this is a tool to create and enable the space and time for your next move. This is delightful, but cannot stand alone without other tools and techniques.