RunScribe RS2KR Pro 2x Fitness Tracker, (Black, Red) Track & analyze advanced running metrics, including: Right vs Left Symmetry, Stride Pace & Length, Step Rate, Foot strike Type, Contact Time & Ratio, Pronation Excursion & Velocity, Impact & Braking Gs Auto start & stop, no need to run with your mobile phone. Upload via compatible iOS or Android device post-run Includes Run Scribe web account with full access to metrics, along with online analysis and comparison tools Includes mounting cradles included for heels and laces and replaceable CR2032 battery Pro 2x captures and reports simultaneous left vs right data