Self defense device that caused victim to pass out NOT STUN GUN?

I remember like 10 years ago in a sportsmansguide catalog they had this device that you would put onto a keychain that emit some kind of wave that would disrupt the brainwaves of your attacker and cause them to faint for 10 minutes. It was NOT a stun gun, does anyone remember this or know what I'm talking about? Any help would be appreciated.