Abstract: A backrest adjustment device includes a bottom board, a support board movable relative to the bottom board, and two opposite linkages pivotally mounted between the support board and the bottom board to drive the support board to move relative to the bottom board to change the distance between the support board and the bottom board. Thus, the two linkages are pivoted to drive the support board to move relative to the bottom board to change the distance between the support board and the bottom board so as to adjust the position of the backrest relative to the seat.

Abstract: A backrest adjustment device includes a bottom board, a support board movable relative to the bottom board, and two opposite linkages pivotally mounted between the support board and the bottom board to drive the support board to move relative to the bottom board to change the distance between the support board and the bottom board. Thus, the two linkages are pivoted to drive the support board to move relative to the bottom board to change the distance between the support board and the bottom board so as to adjust the position of the backrest relative to the seat.

Abstract: A cushion includes a flexible curved main body having a first end formed with a fixed portion and a second end formed with a movable portion, and an elastic mechanism mounted on the main body and biased between the fixed portion and the movable portion of the main body. Thus, the elastic mechanism is stretched by the movable portion of the main body to mate with variation of the curvature of the main body, so that when the main body is pressed and deformed by the user's weight, the main body has a greater elastic action, and the curvature of the main body is changed automatically by the elastic force of the elastic mechanism so as to fit users of different statures and weights.