Flashing rear light for bicycles:
https://www.performancebike.com/axiom-lights-flashback-5-led-tail-light-ax-fb5/p914525
I put one on each side of the stroller handle. I used it in parking garages and people would come up and ask where I got them and said they were a great thing to have.
The stroller handle "tube" is about the same diameter as the bike tube (seat tube) these are intended for, so they mount really nicely also.
Thanks for the memories.. our little ones are done with strollers now..