Patient Selection: Patients seeking the thinnest possible materials, with the most flexibility and versatility. Indications: High rearfoot varus • Heel spurs • Metatarsalgia • Plantar fasciitis. Materials: XT Sprint is a poly-carbon graphite composite. This device comes standard with a high quality vinyl top cover and are most commonly prescribed with a 55 durometer extrinsic rearfoot post (optional).