Ministrel Stack

The AAA miniature battery is of a standardised format and is slightly smaller than the stylus battery.

Pila stilo e ministilo a confronto
Comparison of stylus and mini stylus batteries

The small battery is 44.5 mm high and has an average diameter of 10.5 mm, is widespread in the market in the rechargeable versions at 1.2 Vdc (mainly NiMh) and non-rechargeable at 1.5 Vdc (mainly alkaline).