F series electromagnetic stirrers without heating are especially recommended for continuous operations; the F20 and F40 models are made entirely of sheet metal coated with acid-resistant epoxy paint, whilst the F30 is made of painted cast aluminium alloy making these stirrers very rugged. The different power ratings and strong magnetic force make these instruments ideal for stirring both small and large volumes. The F30 and F40 stirrers are fitted with an illuminated green ON / OFF switch, variable speed motor and relative orange pilot lights showing the instruments are operating.