Caps are fully machined and assembled in the Midwest USA Diesel cap is billet aluminum, with stainless steel locking components. DEF cap is fully machined acetal, with stainless steel locking components. Keys are stainless steel with polypropylene handle. Locking diesel and DEF caps combo for Ford trucks with 6.7 L POWERSTROKE engine. This is compatible with SOME 2020 filler necks. Check carefully. https://youtu.be/OHxp6BVtuLM