I found a 'strobe' (blinky light) which is 9/16" in diameter and 5/8" tall which includes a small spring clip. It has 3 LEDs, one red, one blue and one white (dim relative to the others). Cheap enough and small enough to carry several.
WARNING & DISCLAIMER:
SELECT AND USE OUTDOORS AND SURVIVAL EQUIPMENT, SUPPLIES AND TECHNIQUES AT YOUR OWN RISK. Information posted
on this forum is not reviewed for accuracy and may not be reliable, use at your own risk. Please
review the full WARNING & DISCLAIMER about information on this
site.