noun, noun which may take the genitive case particle 'no'
C size battery; C cell
Refers specifically to the C-size cylindrical battery, commonly used in flashlights and toys. Often used attributively with の.
この懐中電灯は単二型の電池を使います。
This flashlight uses C-size batteries.
単二型は単三型より大きい。
C-size batteries are larger than AA-size batteries.
Compound of 単 (single/cell) + 二 (two, indicating size rank) + 型 (type/model). The numbering system reflects historical battery size classification.