According to NFHS standards, officials must have the correct equipment. Officials may agree to wear long black pants with a 1 1/4" white stripe, similar to football. Only officials may continue to wear white shorts and white over-the-ankle or knee-high socks during the changeover year of Spring 2013. Everyone must agree ahead of time, and everyone must wear the same. All referees carry whistles, which are used to halt play when there is a foul or a violation on the court. To identify the nature of the infringement or to administer the game, hand signals are utilized. Officials at the highest levels of collegiate and professional basketball use a PTS timing device on their belt-line (Precision Timing System).