Polar G1 GPS sensor provides provides accurate speed and distance measurement for a range of outdoor sports. Ultra light (34 g) and small (39x64x12 mm). Measures speed/pace and distance. Records accurate GPS positioning data. Easy to wear with a light GPS clip (26 g). Rechargeable battery (20 hour life) via micro USB. Compatible with following model's: C S600X, RCX3, RCX5, RS800CX.