The classic Blue Aerlog® is a pocket sized, permanently sewn-bound book. The Aerlog® Classic makes transcribing to another Master log book unnecessary. It has a separate "pay section" that is preferred by pilots who like to keep their pay time right next to their flying time. 3.5" x 5.75". The Maroon Aerlog® is an Ultra compact size, with semi-concealed bright wire binding and a water resistant cover. Preferred by pilots who want to keep record only of their flying time and expenses without any cross reference to pay time. 3.25" x 4.375".