A mounting system for a portable device includes a top case, a bottom case coupled to the top case, and first and second arms on two sides of the top case and the bottom case and spaced away from each other. Each of the first and second arms include a first section and a second section. In a first state where the top case is pushed toward the bottom case and a first distance is between the first and second arms, the first sections protrude outside from the top case. In a second state where the second sections are pushed toward each other and a second distance smaller than the first distance is between the first and second arms, the first sections do not protrude outside from the top case or protrude outside from the top case less than in the first state.