Know just how vulnerable an opponent is as Grandmaster Benko teaches you the hyel do (vital points) of the body. Learn how to stop an opponent quickly. There are three primary hyel do categories; tong hyel, relates to vital points which when pressure is applied pain or the reduction of pain will occur. Ma hyel, relates to vital points of the body which if struck or pressure is applies to, will result in some level of paralysis. This paralysis may be temporary, prolonged or permanent. Sa hyel (lethal points), are areas which when struck or pressure in applied to may result in unconsciousness or death.