2010-2017 4Runner Trail Edition 4-Door 1.75" Black RKR Step System (NFBT104RKR4RS4)The main structure of these steps is N Fabs heavy duty rock rails. These rails are engineered for maximum durability, featuring a 1. 75 inch tubular steel construction and a fully welded design for outstanding strength and rigidity. These rails act as rock sliders on the trail, allowing your ride to slide over rocks and other obstacles without damaging the rocker panels. Additionally, these rails provide moderate chip and scratch resistance,