PHOENIX (AP) — NFL owners have passed two rule changes to enhance player safety and are expected to vote whether to ban offensive players from using the crown of their helmets against defenders.

The owners outlawed peel-back blocks anywhere on the field; previously, they were illegal only inside the tackle box. A player makes a peel-back block when he is moving toward his goal line, approaches an opponent from behind or the side, and makes contact below the waist.

Also banned is overloading a formation while attempting to block a field goal or extra point. Defensive teams can now have only six or less players on each side of the snapper at the line of scrimmage. Players not on the line can’t push teammates on the line into blockers, either.