The next piece of the puzzle is Westcans rail caps, which provide many additional tie down points while also protecting the edges of your truck box from dings and scratches! In addition to being extremely functional, these rail caps are contoured to the profile for each available make and model of truck box to give a great fit and finish! All Westcan rail caps have a smooth, sleek finish and are crafted using both marine grade and military grade aluminum., Aluminum;