Hair flatness is usually caused by scalp sebum and haircareproduct residues. Yuanqibang uses siliconefree & glycerinfree formula to reduce residues. Supported by invitro model tests for R&D reference, some users may get subjective voluminoushair experience. Note: These results are in-vitro laboratory model test results, for formulation R&D reference only. They do not represent equivalent effects on human body. Actual user experience may vary.