Food-grade stainless steel, safe, durable and easy to use, much better than the plastic whistles. The solid stainless steel whistle won't readily rust or corrode. Whistles are gifts for coaches, P.E. teacher, referees, linesmen and officials as well as for lifeguards, animal trainers, and traffic police officers, Football Coach, Soccer Coach, Basketball Coach, Volleyball Coach, Baseball Coach, Hockey Coach. These whistles are great for referees, coaches, training, teachers, survival, emergency, school, gym, etc.