A [probably geeky] roadworks question

[FatboyKim]

When a lane closure on a motorway or A-road is in place and cones are used to gradually filter cars into the next lane, there are often orange beacons sat on top of the cones. Said beacons always seem to flash in time to guide cars up the road. How?! Do they have to be programmed, do they 'talk to each other? Is there a 'master' beacon to which all the others are programmed?

You sometimes see the odd one or two out of sync, but they seem to perfectly flash in pattern.

[Tasmin200]

The talk to each other. It's pretty effective at catching your attention.

https://startsafety.uk/taperlamp-sequential-warnin...

[P675]

They just send an IR signal to the one behind them after they flash.

[HelterSkelter]

After a few years of working on the motorway I was suprised to find out how much they cost a unit after not being so gentle with them...