Fudgie,
Not sure about a tail light that flashes, unless it is one of these brake lights.
https://www.kisantech.com/index.php?cat_id=3I've been running one of these for years, and it really gets attention. I've had cagers pull up along side me and say 'your brake lights flash when you stop'... Just what the doctor ordered

Also, I notice that folks stop further back from me than they did without the
SOMA light (
Stay
Off
My
Ass).
Got the one that replaces the 1157, and it comes with the 'flasher' base, and 2 bulbs (very bright).
If ya order from Kissan, ask about the discount for MSF instructor (or in your case, EMT?).
Black Dog