A wearable device configured to be worn by a person, the wearable device comprising: a housing having an inner spine member , wherein the inner spine member comprises a substantially rigid central portion a controller supported by the spine member , the controller having a sensor operably associated therewith, wherein the sensor is configured to detect activity of the person; a display supported by the inner spine member , the display operably connected to the controller ; characterized in that - the inner spine member further comprises a first substantially rigid segment . a second substantially rigid segment . a first flexible zone connecting a first end of the substantially rigid central portion and the first substantially rigid segment , and a second flexible zone connecting a second end of the substantially rigid central portion and the second substantially rigid segment, wherein the first and second flexible zones are curved segments having a concave shape configured to allow flexing of the inner spine member at the first and second flexible zones (46. 48); and - the wearable device further comprises an indicator system supported by the inner spine member , the indicator system operably connected to the controller , wherein the indicator system is illuminable to indicate a level of activity of the person. a housing having an inner spine member , wherein the inner spine member comprises a substantially rigid central portion a controller supported by the spine member , the controller having a sensor operably associated therewith, wherein the sensor is configured to detect activity of the person; a display supported by the inner spine member , the display operably connected to the controller ; characterized in that - the inner spine member further comprises a first substantially rigid segment . a second substantially rigid segment . a first flexible zone connecting a first end of the substantially rigid central portion and the first substantially rigid segment , and a second flexible zone connecting a second end of the substantially rigid central portion and the second substantially rigid segment, wherein the first and second flexible zones are curved segments having a concave shape configured to allow flexing of the inner spine member at the first and second flexible zones (46. 48); and - the wearable device further comprises an indicator system supported by the inner spine member , the indicator system operably connected to the controller , wherein the indicator system is illuminable to indicate a level of activity of the person. - the inner spine member further comprises a first substantially rigid segment . a second substantially rigid segment . a first flexible zone connecting a first end of the substantially rigid central portion and the first substantially rigid segment , and a second flexible zone connecting a second end of the substantially rigid central portion and the second substantially rigid segment, wherein the first and second flexible zones are curved segments having a concave shape configured to allow flexing of the inner spine member at the first and second flexible zones (46. 48); and - the wearable device further comprises an indicator system supported by the inner spine member , the indicator system operably connected to the controller , wherein the indicator system is illuminable to indicate a level of activity of the person. <EOS>