A6 paper size (105mm × 148mm)
Refers specifically to the ISO 216 A6 paper size, commonly used for pocket notebooks, postcards, and small booklets.
This notebook is A6 size, making it convenient to carry around.
Standard notation using the Latin letter A and Arabic numeral 6.
Variant using the kanji numeral 六; less common but still encountered.
From the ISO 216 A-series paper size designation 'A6' combined with 判 (はん, 'size' or 'format').