noun, noun which may take the genitive case particle 'no'
AAAA battery; AAAA size
Refers to the AAAA battery size, a small cylindrical battery. Often used attributively with の.
このリモコンは単6型の電池を使います。
This remote control uses AAAA batteries.
単6型の電池はあまり一般的ではない。
AAAA batteries are not very common.
Compound of 単 (single/cell) + 6 (six) + 型 (type/model), following the naming pattern for cylindrical battery sizes.