Two parts that do the security work: the code and the latch

The first vented shutter came off the line in 1998. Almost everything added since has gone into two parts a buyer never sees — the rolling code in the handset and the latch at the bottom rail.

The first vented roller shutter came off the line in 1998. The curtain has changed since, but most of the engineering has gone somewhere else: into the code that opens the door and the latch that holds it shut.

The handset uses ARC rolling code. Each cycle retires the code it just used and issues the next from a very large space, so a code captured off the air will not open the door a second time. This is the difference between a shutter and a gate with a fixed-code fob, and it is invisible until someone tries.

The latch is the mechanical half. It throws as the curtain lands and withdraws as it lifts, drawing no power of its own — so it still holds through a cut, and it still holds if the headbox floods. A mechanical key withdraws the bolt when the door has to be raised by hand. Without it, a closed shutter can be levered up at the bottom rail, which is the opening a forced entry looks for first.

Around those two sit the alarms: forced-entry, fire, power loss and flooding, all reported at the control box. They are the cheap part. The code and the latch are what the door stands on.