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 higher price is prohibited. (Available in D, G, and F, and a set of ♭B, C, and A, with a triangular prism that can be fixed with a light turn.) This allows beginners and those new to the erhu 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 should choose a suitable length from 39 cm, 41 cm, or 37 cm according to your physique and playing style. For example, if a physically large man finds that the spacing between his fingers is too tight when playing the third position with an effective string length of 39 cm, making it difficult to finger smoothly, 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 she cannot reach the correct intonation position for the little finger in the first position of D major without shifting her hand downwards 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