Nike+ Fuelband SE Fitness Tracker Available in three sizes: small (5.79 Inch/147mm), medium/large (6.77 Inch/172mm) and extra-large (7.76 Inch/197mm) Includes two easy-to-insert links (.32 Inch/8mm and .63 Inch/16mm) for a fine-tuned fit USB charging cable and sizing tool included Ambient light sensor detects environmental light levels and adjusts accordingly Bluetooth 4.0 pairing to smart phones