The RB20 Slim Line Running Boards offer the same heavy duty toughness as the original RB Series, but with a slimmer design that fits tighter along the cab for increased ground clearance when off-roading. Constructed from 16-gauge zinc-coated galvanized steel, the Raptor-inspired boards are 5-1/2 inches across at its widest point (compared with 7-1/2 inches of the original RB20).