Details of Best Genius Hair Extensions 100 g/ pack normally Could be cut at any point for easy customization No return hair 0.8 mm thick and 1.7 mm tall Easy application Could custom Package Longer lasting and durable Highest quality 100% remy human hair or virgin hair Genius weft is the hot-selling wefts, which is between flat weft and hand-tied weft, featuring flattest and the most lightweight weft as well as attractive price.