Sorry, but it would not link to the specific thread, but I did indicate where on the site to find the information. Mr. McClung had a problem with people pasting excerpts from his site without proper reference, thus not allowing the specific thread to be linked.
Some of those "hybrids" contain kevlar "fiber" not the actual thread, which does not afford the same properties of the all kevlar vests. The laminates of different types of "goldflex", "spectra" and some other trade names of aramid fibers do not offer the same protection as kevlar. Vest companies are attempting to construct lighter, more comfortable vests made of the hybrids, but unfortunatly they don't protect like kevlar.
Any LEO needs any further in depth info on vest materials contact:
Kevin McClung
MD Labs
8333 Pecos Dr
Prescott Valley, Az
928-772-3021
He runs Tactical Forums and has a specific LE section. poke around, an awful lot of info to look over. He was also responsible for bringing the zylon issue to light. It's sad that it took an officer losing his life and several others suffering wounds for it to become an issue.