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 (D1) from the upper portion of the first support segment ; the third support segment extends in the first direction (D1) 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 (LI); 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 (L2), 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 (D1) from the upper portion of the first support segment ; the third support segment extends in the first direction (D1) 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 (LI); 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 (L2), 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. <EOS>