A 2-1-2 forecheck is man-on-man defense. Wingers (or F1 & F2) lock onto opposing Ds. The center (or F3) stays with his counterpart. Ds gap up to opposing wingers. This aggressive formation demands concentration, as dangerous gaps open whenever individuals are late to their checks. The 2-1-2 is most often seen following a faceoff loss, when forecheckers have an easier time attaching to their marks.