Ponytail extensions offer flawless and glamorous hair in minutes. If you’re wondering if ponytail extensions are heavy, look at what hair fibers it's made with. The hair fibers on a ponytail hair extension determine how heavy it is. A human hair ponytail is a little more dense than a synthetic ponytail. If you want a lighter weight style, get a ponytail made with a synthetic fiber. If you want a ponytail extension that gives you a natural look, check out human hair ponytail extensions.