In 2001, following the terrorist attacks of September 11, when play resumed and for the balance of the season all MLB teams including the Mets had an American flag patch sewn onto the back of the collar of all game jerseys. The Mets added embroidery to the right sleeve cuff of all five jerseys showing the phrase "9-11-01" flanked by two American flags. In addition, beginning September 21 at their first home game after the attacks, the Mets wore caps of New York City's first-responder agencies—the Police Department (NYPD), Fire Department (FDNY), Emergency Medical Services (EMS) and Port Authority Police (PAPD)—in place of their regular game caps. The Mets were only permitted to wear these caps during pre-game warmups on September 21 but defied MLB instructions and wore them in game play, that night and for the remainder of the season. All of the first-responder caps were navy blue, with either "NYPD" in white serif lettering, "FDNY" in thick yellow-orange-red gradient lettering, or the EMS or PAPD shield logo on the front. Typically, each player and coach chose one of the caps and wore that same one for the balance of the season.