The AMRAP lacrosse ("LAX") balls are an excellent way to loosen up those tight muscles, and work on your mobility. Lacrosse balls are an effective and inexpensive mobility tool used for self-myofascial release which will improve your flexibility, increase your performance, and reduce injuries. Because of the small size you can take one with you in your gym bag, have one at your desk and one in your car. There is only one thing you can't do when you have them: telling excuses!