These are triangular filament synthetics which because of their structure repel water. These materials also tend to trap air between the filaments which allows them to float or gather bubbles.
Loose un-twisted yarn made from triangular, translucent, fine diameter filaments, untwisted like large diameter floss. May be used for wings, shell-backs, trailing shucks, air bubbles, wrapped like floss or chopped and blended for dubbing or mixed with fur. Extremely visible in fluorescent colors when used for loop wing parachute posts or dry fly wing topping. Antron collects air bubbles and repels water. Spooled.