The NFL and the league office said Monday they are investigating reports that a number of players who have played in the past have used the color black paint on their uniforms.
The league office confirmed the report but would not provide further details.
Black paint is a controversial paint used by many players in the NFL who are black, including defensive end Michael Bennett, who has a black faceplate on his helmet.
Bennett’s teammates have also been criticized for using black paint.
The players union has called for a moratorium on using black color on uniforms.
NFL Commissioner Roger Goodell has previously said he would look into the issue.