A mobile device case for receiving a mobile device. An inner wall defines an opening in a base side. The base side includes at least one recess that includes a stop. The opening receives a male portion of a male-female connection. The stop is positioned to prevent 180 degrees of relative rotation between the mobile device case and the male portion. The mobile device case and an accessory form an assembly. When the male-female connection is formed, the mobile device case and the accessory are coupled together. In one embodiment, the stop is configured to contact the male portion in one rotational direction so that to decouple the mobile device case and the accessory, relative rotation is reversed. The opening may be an oval.