Schultz's instinct was right: Conventional prosthetic legs couldn't stand up to his high-impact lifestyle. So in early 2009, he designed and built a limb that could. Its key feature was the Moto Knee, which uses an adjustable 250psi mountain bike shock absorber to regulate the joint's stiffness with compressed air. But snowboarders and skateboarders also require critical toe pressure and ankle tension, so Schultz added the Versa Foot—a foot-ankle assembly that also uses a pneumatic shock absorber to emulate joint resistance. Together, the two parts complete an artificial lower limb that's impact-resistant, waterproof, and quickly customizable for a range of high-performance activities.