Truck and SUV manufacturers are incorporating more and more technological gadgets into their vehicles with the goal of enhancing off-highway performance and safety. One that is becoming nearly universal is hill-descent control. I was dubious of the system at first, but after driving several vehicles equipped with it, I have to say it does a better job than I can do in my manual-transmission FJ40 using engine braking along with threshold application of the brake pedal. Yes, you're relying on a mechanical aid, and I believe you should also practice the skills to do without it just in case something fails, but otherwise it's a brilliant invention and makes negotiating a very steep downhill slope child's play.
I'm going to be publishing a series of short videos on various systems such as this, for those not already familiar with them. Here is the first one, on our Vimeo channel (click on the title to go to the full-size version):