You are now in the section with Paperblank notebooks in Midi format. The format of these is approx. 120 mm x 180 mm. It varies what they are for GSM on the paper, it depends on whether the cover is soft or hard. If you want to read more about differences in different sizes with measurements, you have the information here. Here you quickly land in the right department if it wasn't Midi that you were looking for. From largest to smallest: Grande Ultra Maxi Mini