A bracket assembly, comprising: a first bracket including a first support segment, a second support segment, and a third support segment, wherein the first support segment has an upper portion and a lower portion; the second support segment extends in a first direction from the upper portion of the first support segment; the third support segment extends in the first direction from a portion of the first support segment that is adjacent to the lower portion of the first support segment; and the first support segment, the second support segment, and the third support segment jointly define a support passage; and a second bracket mounted in the support passage of the first bracket and including a first wall, a second wall, and a third wall, wherein the first wall corresponds to the first support segment of the first bracket, the second wall corresponds to the second support segment of the first bracket, and the third wall corresponds to the third support segment of the first bracket, and wherein the first support segment of the first bracket includes a first feature; the first wall of the second bracket includes a second feature; the first feature and the second feature are not abutted against each other when the first bracket and the second bracket are extended with respect to each other to a first length; and the first feature and the second feature are abutted against each other when the first bracket and the second bracket are extended with respect to each other to a second length, characterized in that the first feature is one of a projection and an elastic arm, and the second feature is the other one of the projection and the elastic arm. a first bracket including a first support segment, a second support segment, and a third support segment, wherein the first support segment has an upper portion and a lower portion; the second support segment extends in a first direction from the upper portion of the first support segment; the third support segment extends in the first direction from a portion of the first support segment that is adjacent to the lower portion of the first support segment; and the first support segment, the second support segment, and the third support segment jointly define a support passage; and a second bracket mounted in the support passage of the first bracket and including a first wall, a second wall, and a third wall, wherein the first wall corresponds to the first support segment of the first bracket, the second wall corresponds to the second support segment of the first bracket, and the third wall corresponds to the third support segment of the first bracket, and wherein the first support segment of the first bracket includes a first feature; the first wall of the second bracket includes a second feature; the first feature and the second feature are not abutted against each other when the first bracket and the second bracket are extended with respect to each other to a first length; and the first feature and the second feature are abutted against each other when the first bracket and the second bracket are extended with respect to each other to a second length, characterized in that the first feature is one of a projection and an elastic arm, and the second feature is the other one of the projection and the elastic arm.