noun, noun which may take the genitive case particle 'no'
AAA size (battery)
Refers specifically to the AAA battery size, commonly used in small electronic devices. Often used attributively with の.
This remote control uses AAA batteries.
Please buy some AAA dry-cell batteries.
D size battery, much larger than AAA.
Standard kanji spelling using the numeral 4.
Variant using the kanji numeral 四; less common but still seen.
Compound of 単 (single, unit) + ４ (four) + 型 (type, model), referring to the fourth standard single-cell battery size in the Japanese classification system.