A baler is provided that includes a housing that defines a baling chamber and a plunger movable along an axis within the baling chamber to compress the crop material. The baler includes a first guide rail coupled to an exterior surface of the baling chamber and a second guide rail coupled to the exterior surface of the baling chamber. The baler includes at least one bearing coupled to the plunger to guide a movement of the plunger within the baling chamber. The bearing has a first bearing surface, a second bearing surface and a third bearing surface. The first bearing surface engages the first guide rail, the second bearing surface engages the first guide rail and the third bearing surface engages the second guide rail to constrain a vertical movement and a lateral movement of the plunger relative to the baling chamber.