Just like all of our Pro Series Tool Boxes are made from .120 aluminum. All of our Pro Series Boxes come predrilled for all ITD accessories. Just pop out the plastic plug in the pre-drilled holes and bolt the accessory on. From a bolt on storage fender to a bolt on shelf; having your tool box set up the way you want it has never been easier. Pro Series boxes were built for those of you who make your living with your trucks. Made in the USA.