This signal is used by the Referee to indicate that a facemask has been illegally contacted.
It is possible, but rare, for a facemask foul to be called against the defense without it being called a personal foul. All facemask fouls by the offense, and by any player following a change of possession or dead-ball, are personal fouls.
Penalty15 yards for a personal foul (and an automatic First Down if by the defense)
The foul may be preceded by the personal foul signal (S38) depending on the severity of the offence. Bring one hand to the lower face in a grasping motion and bring downwards by 6 inches in an unhurried motion.
Finally point to the offending team by stretching an arm out from the shoulder to the horizontal.