Interchangeable cases for biometric monitoring devices

A band configured to be worn on a person's limb, the band comprising:

• a pocket region, wherein:
• the pocket region has a pocket;
• the pocket is formed between a first layer of flexible material and a second layer of flexible material, and
• the pocket is sized to allow a biometric tracking device associated with the band to be fully inserted within the pocket;
• and
• a slit in an exterior textile layer of the band, wherein:
• substantially all of the slit extends in a direction substantially parallel to the person's limb when the band is worn on the person's limb,
• the slit is shorter in length than a longest dimension of the associated biometric tracking device, and
• the slit permits the biometric tracking device to be fully inserted into the pocket;
• and
• the first layer of flexible material is a mesh through which a display on the biometric tracking device is at least partially visible when the biometric tracking device is fully inserted into the pocket with the display facing the first layer and with content displayed on the display.