Extensor tendonitis flip flops are a type of footwear that helps to protect the Achilles tendon and the calf muscles from injury. Symptoms of Achilles tendonitis include pain and stiffness in the Achilles tendon and calf muscle, and difficulty walking. Extensor tendonitis flip flops can help to prevent Achilles tendonitis by providing support and cushioning to the Achilles tendon and calf muscles. The risk of other overuse ailments, such as plantar fasciitis, can also be reduced by wearing flip-flops, such as when doing yard work.