Correct - very interesting .... but from the web site descriptionHere are some options. The SL2000 looks interesting.
https://spieglerusa.com/lights-indicators/kellermann-turn-signals.html
Quote Part: K110.200 LED bra end blinker , black, Longlife Protection Guard®, IC operated, 330 kHz unquote
they would need to be very bright to shine through the female riders clothing!