A bumper assembly for a vehicle, the bumper assembly comprising: a pair of longitudinally-disposed side rails, wherein each of the pair of side rails comprises an outboard portion and an inboard portion; a laterally-disposed bumper beam coupled to and between the pair of side rails; and a pair of crush cans disposed between the bumper beam and the side rails; wherein each of the pair of crush cans comprises: a box structure comprising a front portion and a rear portion and defining a longitudinal axis, wherein the front portion of the box structure comprises or is adapted to be coupled to a bracket assembly that is adapted to be coupled to the bumper beam, wherein the rear portion of the box structure is adapted to be disposed within the associated side rail, and wherein the rear portion of the box structure defines a plurality of lateral holes; and one or more internal sleeves disposed around the plurality of lateral holes within and coupled to interior surfaces of the box structure, wherein the one or more internal sleeves define a plurality of lateral channels that are aligned with the plurality of lateral holes of the rear portion of the box structure; wherein the plurality of lateral holes of the rear portion of each box structure and the plurality of lateral channels of the associated one or more internal sleeves are adapted to be aligned with a plurality of holes defined by the outboard portion and the inboard portion of the associated side rail when the rear portion of the box structure is disposed within the side rail and collectively receive a plurality of bolts therethrough. a pair of longitudinally-disposed side rails, wherein each of the pair of side rails comprises an outboard portion and an inboard portion; a laterally-disposed bumper beam coupled to and between the pair of side rails; and a pair of crush cans disposed between the bumper beam and the side rails; wherein each of the pair of crush cans comprises: a box structure comprising a front portion and a rear portion and defining a longitudinal axis, wherein the front portion of the box structure comprises or is adapted to be coupled to a bracket assembly that is adapted to be coupled to the bumper beam, wherein the rear portion of the box structure is adapted to be disposed within the associated side rail, and wherein the rear portion of the box structure defines a plurality of lateral holes; and one or more internal sleeves disposed around the plurality of lateral holes within and coupled to interior surfaces of the box structure, wherein the one or more internal sleeves define a plurality of lateral channels that are aligned with the plurality of lateral holes of the rear portion of the box structure; a box structure comprising a front portion and a rear portion and defining a longitudinal axis, wherein the front portion of the box structure comprises or is adapted to be coupled to a bracket assembly that is adapted to be coupled to the bumper beam, wherein the rear portion of the box structure is adapted to be disposed within the associated side rail, and wherein the rear portion of the box structure defines a plurality of lateral holes; and one or more internal sleeves disposed around the plurality of lateral holes within and coupled to interior surfaces of the box structure, wherein the one or more internal sleeves define a plurality of lateral channels that are aligned with the plurality of lateral holes of the rear portion of the box structure; wherein the plurality of lateral holes of the rear portion of each box structure and the plurality of lateral channels of the associated one or more internal sleeves are adapted to be aligned with a plurality of holes defined by the outboard portion and the inboard portion of the associated side rail when the rear portion of the box structure is disposed within the side rail and collectively receive a plurality of bolts therethrough.