A support module configured to be mounted behind a shop window, comprising: a housing framework including a top side, a bottom side, a front side, a rear side, left and right sides, a receiving space defined between said top and bottom sides, between said front and rear sides, and between said left and right lateral sides, a front opening formed at said front side in communication with said receiving space, and at least one lateral opening formed at one of said left and right sides in communication with said receiving space; two guide rail units respectively disposed at said top and bottom sides of said housing framework within said receiving space and spaced apart from each other, each of said guide rail units including two slide rails spaced apart from each other in a left-right direction; and a carrier connected between said guide rail units and movable on said guide rail units toward and away from said front opening, said carrier being slidably connected to said slide rails of said guide rail units to move backward from said front opening or forward towards said front opening; wherein each of said slide rails includes a linear rail member extending in a front-rear direction, and a sliding block slidably connected to said linear rail member; wherein said carrier includes two upright rods spaced apart from each other in the left-right direction for securing a plurality of display modules thereto, and a plurality of transverse rods connected between said upright rods and spaced apart from each other in a top-bottom direction, each of said upright rods having a top end connected to said sliding block of one of said slide rails of one of said guide rail units and a bottom end connected to said slide block of one of said slide rails of the other one of said guide rail units; characterized in that each of said slide rails further includes two stop blocks disposed respectively on front and rear ends of said linear rail member, one of said stop blocks being used to abut a front side of said sliding block when said carrier is placed at a front position, the other one of said stop blocks being used to abut a rear side of said sliding block when said carrier is placed at a rear position; and wherein each of said slide rails further includes a track brake pivotally connected to said sliding block, said track brake being rotatable relative to said sliding block to be placed in pressing contact with said linear rail member for locking said sliding block against movement. a housing framework including a top side, a bottom side, a front side, a rear side, left and right sides, a receiving space defined between said top and bottom sides, between said front and rear sides, and between said left and right lateral sides, a front opening formed at said front side in communication with said receiving space, and at least one lateral opening formed at one of said left and right sides in communication with said receiving space; two guide rail units respectively disposed at said top and bottom sides of said housing framework within said receiving space and spaced apart from each other, each of said guide rail units including two slide rails spaced apart from each other in a left-right direction; and a carrier connected between said guide rail units and movable on said guide rail units toward and away from said front opening, said carrier being slidably connected to said slide rails of said guide rail units to move backward from said front opening or forward towards said front opening; wherein each of said slide rails includes a linear rail member extending in a front-rear direction, and a sliding block slidably connected to said linear rail member; wherein said carrier includes two upright rods spaced apart from each other in the left-right direction for securing a plurality of display modules thereto, and a plurality of transverse rods connected between said upright rods and spaced apart from each other in a top-bottom direction, each of said upright rods having a top end connected to said sliding block of one of said slide rails of one of said guide rail units and a bottom end connected to said slide block of one of said slide rails of the other one of said guide rail units; characterized in that each of said slide rails further includes two stop blocks disposed respectively on front and rear ends of said linear rail member, one of said stop blocks being used to abut a front side of said sliding block when said carrier is placed at a front position, the other one of said stop blocks being used to abut a rear side of said sliding block when said carrier is placed at a rear position; and wherein each of said slide rails further includes a track brake pivotally connected to said sliding block, said track brake being rotatable relative to said sliding block to be placed in pressing contact with said linear rail member for locking said sliding block against movement.