High quality files with the patented 180 degrees mechanism which opens 50 wider and allows filing from both sides mechanism has been tested 12 000 times and will prongs will always align guaranteed for 5 years 50 mm spine holds up to 350 sheets of paper made from heavyweight 100 recycled board covered in wipeclean polypropylene with thumbhole rado rings and metal shoes pocket on spine for easy personalisation and can be updated when the contents change