The DEFBooty manufactured by DEFBooty LLC is a disposable protective cover that slips over the outside of the DEF cap. It prevents dust, dirt and other contamination harmful to the SCR system on new diesel equipment from collecting around the fill port. It also clearly identifies where to add DEF preventing refueling mistakes. By limiting the spread of contamination in the first place, users can ensure more up-time, reliability and longevity for the entire SCR system. The DEFBooty also extends life cycles of the DEF filter, according to the company.