Go Rhino 07-21 Toyota Tundra Crew Max 4DR RB10 Slim Running Boards Kit (Incl. Brackets) - Tex. BlkThe RB10 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 were built to protect your panels from flying debris while providing a full length step platform. The classic louvered design is four inches across at its widest point