The advantage of a tri-fold clipboard is the additional side pockets that sit on either side of the pilot's knee. The top surface (the middle piece in the illustration on the left) is a normal clipboard which holds charts and worksheets during flight. Backup documents and charts will fit in the side pockets. This Jeppesen model easily holds lots of folded aeronautical charts in the side pockets, and it comes with a free IFR flight planning chart. One nice feature of the Jeppesen trifold kneeboard is the way it folds up after use. There are no loose velcro ties flapping around; everything folds up into a nice compact unit for after-flight storage.