A Hi Res file set is a combination of three digital files for one photo.
What you get when you order a Hi Res file set is a CD with three jpg files for each photo orderd ($25/photo) an original, a file ready to print an 8x10 and a file ready to print a 5x7. These files are burned on to a CD that has one of the photos printed directly on the CD. Unless requested otherwise multiple file sets will be burned on a single CD.