Abstract: A protective cap for covering the sidewalls of a pickup truck bed is provided. The caps have a contour matching the contour of the sidewalls so as to provide a close fit, without the use of spacers or shims. The cap includes an elongated body with opposite forward and rearward ends and opposite inside and outside edges. Inside and outside lips are formed by bending portions of the respective inside and outside edges of the body downwardly. A notch is provided adjacent the rearward end of the body, to permit a rearward lip to be formed by bending a portion of the rearward end downwardly. The formation of the outside and rear lips closes the gap. The outside lip and rear lip are joined by a weld which fills the closed notch so as provide a continuous curved surface at the rearward corner of the body. The weld is polished to be visually indistinguishable from the outside and rear lips.