Why buyers choose it

Fitted at the meter, not the panel

In series where the meter joins the bus, which is where the surge arrives.
Small enough for the chamber

Fits in the space that already exists, so it is installed on the same visit as the meter.

A part, not a programme

Replacing a protector after a storm is a component; replacing a riser of electronics is not.

In detail

A wired bus running between buildings is a long conductor, and a long conductor is what a lightning surge travels down. The meters at the end of it have electronics that cost more than the cable.

This fits in series at the point where a meter joins the bus. It is small enough to sit inside the meter chamber and simple enough that fitting it is part of the same visit as fitting the meter, which is the only way protection actually ends up installed.

It is the cheapest component in a wired scheme and the one whose absence is most expensive: replacing a surge protector is a part; replacing a riser of meter electronics after a storm is a programme.