Terahertz Gua Sha Set 99.97% or more Not 15N, which is polished from natural stone. For beginners. Terahertz Gua Sha is the same as 15N if it is 99.7% or more, but some repeat customers say it's different, so please purchase 15N if you are looking for a high-end product. Unlike 15N, which is polished, it cannot be used for water. #Terahertz Care: Stiffness relief Care: Stiffness relief, Lift-up Areas: Eyes Areas: Eyes, Face Areas: Eyes, Face, Legs Areas: Eyes, Face, Legs, Whole body