Modular system for watch

A watch comprising:

• a body comprising:
• a housing having a first side and a second side opposite the first side;
• a controller within the housing;
• a display supported on the first side of the housing;
• and
• a touch sensor configured to receive a touch input at the display;
• and
• a functional module removably attachable to the second side of the housing and comprising an electronic component operably connected to the controller when the functional module is attached to the second side of the housing, the functional module being exchangeable with other functional modules that are removably attachable to the housing.

A system comprising:

• a watch body comprising:
• a housing;
• a controller within the housing;
• and
• an attachment element;
• band retaining features on opposing sides of the housing;
• a watch band releasably connectable to the housing by the band retaining features;
• a first functional module comprising a first electronic component for performing a first function, wherein the first electronic component is operably connected to the controller when the first functional module is attached to the attachment element;
• and
• a second functional module comprising a second electronic component for performing a second function, different than the first function, wherein the second electronic component is operably connected to the controller when the second functional module is attached to the attachment element.