Most app developers have few incentives to build their own hardware, let alone the resources. With 25 million mobile users, Runtastic has both — so it only makes sense that the company is bringing a slate of complementary exercise gear to the US for the first time. The initial catalog won’t shock cyclists and runners who have ever toyed with tracking their progress, but it’s certainly complete. Along with Runtastic’s take on a GPS watch ($150), there’s also an app-friendly heart rate monitor ($70), a speed sensor ($60), an armband and a bike mount. While the peripherals only truly make sense for Runtastic loyalists, they’re available today through Amazon — and they might seal the deal for athletes who want a harmonious blend of hardware and software.