High quality spring: use high-strength steel sheet spring, durable, not rusty, not easy to fall off after pinching, not easy to damage, long service life, stable performance. TEETH CLIP - The advantage of the serrated clamp is that it can be fixed firmly in place even in thick books. The contact surface with the book is smooth and will not damage the paper. Thickness measurement: check whether the thickness is relatively thick, and transparency and shine are good materials. Environmentally friendly material: green and environmentally friendly, non-toxic and tasteless, guarantees the health of you and your family. Applicable products: all musical instruments, as well as books, music stands, electric piano, electronic organs and other music equipment.