I purchased the one piece volumizer that is 100% human hair. It is absolutely NOT 100% human hair! First, when I curl it or straighten it, on the lowest heat setting, it smells like plastic is burning. Second, it does not hold a curl whatsoever! I have tried curling it every way imaginable, even clipping the curls in place and letting it sit for a few days and it still does not hold. I don't believe the piece is 100% synthetic, but it definitely is a synthetic blend and they're falsely selling this piece as 100% human hair. I've had synthetic blend extensions before and it has that same burning plastic smell. Total waste of money! Even when wearing it straight, without styling it, the ends separate and look stringy. You can totally tell I'm wearing an extension. It only looks decent for the first 10 minutes. Absolute garbage!