Adjusting the wrong sound needs a set of professional tuning tool. abrasion resistance. Weight: 390g / 13.7oz Sturdy and smooth handle. L-shape design, easy to use it. Small and exquisite, convenient to carry. Specially designed for tuning of Guzheng and for most machine devices that have quadrilateral opening. In order to maintain the accuracy of piano sounds, regular inspection by a professional is necessary. colour:brown Material:Metal + plastic size:15.5 x 3.8 x 2cm Inner bore size: . 0.65cm / 0.26in Handle Length: . 10.5cm / 4.13in Package Contents: 5 x Tuning Wrench Note: Please measure the tip size of your device before purchasing, make sure the size of your devices match with the wrench quadrilateral Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.