Footballers wear what look like sports bras because they are actually GPS tracking vests designed to monitor and measure the players' performance on the field. These vests contain a GPS device and other sensors that track metrics such as distance covered, speed, heart rate, number of sprints, and overall physical load. The data collected helps coaches, trainers, and sports scientists analyze player movements and fitness, optimize training, prevent injuries, and make tactical decisions during matches. The vest is designed to be tight-fitting to keep the GPS device in the correct position between the shoulder blades for accurate data collection. This technology is widely used by professional football clubs and international teams during training and games, and although it resembles a sports bra, its purpose is purely for performance tracking rather than any form of support or protection traditionally provided by bras.