https://kisantech.com/mag/tailblazer/100hd.htmlI imported these when I was in business, with the argument that as they were on from the time the brakes were applied, they were legal. What they actually did was to modulate the brake light itself. In other words they would dim down then back to bright rapidly for 2-3 seconds before going solid red.
The thinking behind this was it was an attention grabber the same as headlight modulators - which are 100% legal in Australia I might add.
Blinking red brake lights aren't legal as they can appear to mirror emergency vehicles and the cops take a dim view of people copying them.
The example link above relates to a unit wired directly into your brake wire - there are others which have the modulator built into the back of replacement tail/brake light bulbs.
Incidentally the 100HD was the only one suitable for ST1300.