The zippers on both sides of the trouser legs are zippers that can be quickly put on and off. When you are ready to go on stage after training, you can quickly take off your pants and put them on. These are all used by football players. Usually wear football shorts when warming up, and you can quickly take off your pants by unzipping when playing ball. You don't even have to take off your football shoes. In addition, when the weather is hot, you can unzip the zipper to make your feet or legs more ventilated and cool. I used to buy club training clothes with this zipper on my pants.