That's an AFFF with a revolving head, temperature activated.
Basically above a certain temperature the foam comes out and is
sprayed around the compartment. Sort of like a fire activated
sprinkler head (which whirls round in the jet of water creating a
spray).

I suspect the modern version is a pressurised tube type (Firetrace and
others), the tube melts at the locality of the fire and distributes
"whatever" all over it until exhausted. They are very expensive, about
£120-180 as I recall. Beware using powder on metals like aluminium,
they will put the fire out - but at the expense of that item
usually :-)

AFFF foam do not "go off" in the way that powder do - which settle and
go rigid inside thus are important to service often.