Tulis Heavy Duty Heel Cups are twice as thick, and, offer all the comfort you expect from our Classic Heel Cups, and also deliver the heavy-duty protection you need from heel strike pain during sports activities such as volleyball, soccer, basketball and tennis. They work best in: athletic shoes, cleats, work boots and more spacious lace up shoes. They are ideal for plantar fasciitis, Achilles tendonitis, Severs disease, shin splints, and heel pain.