Modern knock-off of what used to be a very common universal aftermarket accessory. They go all the way back to the model T era and I think the marketing was about not slipping more than protecting the running boards.
Deceptive of classic parts to not give better pictures
This came off a 1948 tandem axle AD truck about 45years ago, this was on passenger side, drivers side is worn smooth so they had been on the truck for some time and a forest had grown around the truck before I found it.
I plan to use this as a pattern and get 2 new ones cast someday
edit : the logo in center is 'never slip'