Drawer system for a 2018 or similar Ram 2500/3500.  My understanding is that this fits both long and short bed as they only made one length. It's a few years old.  It's not the newest model.
I am the second owner. Previous owner only used for a few months.  ONLY reason for getting rid of it is that I traded in Mt truck and have a GMC now and don't want to cut it up to fit.