This product is a brand new, genuine product from the Erhu Master Hall brand. When purchasing, it is intended for personal use, and resale at a high price is prohibited. (Available in D, G, and F, and a 2-piece set of ♭B, C, and A, with a triangular prism that is fixed with a light turn.) This allows Erhu beginners and novices to easily play with "correct intonation." Advice on choosing the length of the intonation display device: Generally, the effective string length of the Erhu (the length from the bridge to the qianjin) is set to 39 cm. The intonation display device is based on an effective string length of 39 cm, and you can choose a suitable length from 39 cm, 41 cm, or 37 cm according to your physique and playing style. For example, if a large-built man finds that the finger spacing is too tight and the fingering is not smooth when playing the third position range with an effective string length of 39 cm, he should extend the effective string length to 41 cm and select an intonation display device of the same length. Conversely, if a relatively small woman finds that the little finger of the "D major first position" does not reach the correct intonation position unless she slides the thenar eminence down with an effective string length of 39 cm, she should shorten the effective string length to 37 cm and choose an intonation display device of the same length. Utility Model Registration No. 3180571 Product Name: Erhu Intonation Display Device Contents: 2 intonation display rods, 4 attachments, a dedicated case, and an instruction manual