Nerf bars were never sliders, or rock rails.Hmm, I haven't seen Slee's 250 solution, but the factory sliders appear just as beefy as his 80 and 100 products.
When Toyota had their FJC design team out to meet with Rising Sun in 2005, they explained that "sliders" conjures up images of little hamburgers so they use the term rock rail. I remember when Bruce Miller was making them for 40s at EPOCHS Mfg. he was calling them nerf bars.
They were those tube bars that come factory or added later, but mostly just a step.
