The diablo sport predator is a hand held programmer that plugs into the OBD port. You can change some perameters of the truck and put different tunes into the truck. Like a performance tune for 91 octane or such. It also helps eliminate MDS as an option. I never found MDS activated to be worth more than a tenth or two of a mile. I average about 15 in the winter with a lot of idle time warming up, and about 16 or 17 in summer months. It also helps with transmission shifting and overall makes the truck drive a bit better. They were very popular before phone based app tuning and was a better alternative to using a laptop to make the changes. It's about half the size of a shoebox for packaging and there's only 4 buttons so it's pretty basic.