A biometric monitoring device and multiple carrying cases for same are provided. In some implementations, the case may be made from a flexible viscoelastic material and the biometric monitoring device may be slipped into a receptacle in the case through an opening in the case; the opening may become distended during the insertion of the biometric monitoring device. In some implementations, the case may feature a display window that, in combination with materials of the biometric monitoring device, may mask a display of the biometric monitoring device from view when the display is off and may allow the display to be seen when the display is displaying content.