Not a recommended strike; both for it’s effectiveness, and for it’s potential danger to the opponent (though I’ve heard contrary statements from various instructors). There is still the potential to break the trachea of an opponent, and strikes with knuckle or inner hand are recommended to be avoided in favor of a fist.
This information is for Brady J. Frey's personal training records & is not intended as a replacement for live, professional Krav Maga training. I am in no way responsible for your disregard to this warning. Please contact me if you have questions.