Atoma's Bio series of notebooks features environmentally friendly cardboard covers and biodegradable rings. It utilizes Atoma's patented binding system, which allows the user to add, remove or chage the pages without damaging the paper or the notebook. The weight of the paper is 90gr. The A4 size and the A5 size notebooks contain 144 pages of squared paper with margins. The A6 size notebook contains 120 pages of squared paper.