This bow straightener specially designed for adults and children. If you are learning the violin, I believe that the bow straightener can play a role during your practice. Use the bow straightener to avoid playing in the wrong posture. Features -Color:Black -Material:Rubber -Size:1.50X4.50X10.00cm/0.59X1.77X3.93in; 1.50X1.50X9.50cm/0.59X0.59X3.73in; 1.00X1.00X8.00cm/0.39X0.39X3.14in - Note: 3/4-4/4, 1/2-/1/4, 1/8-1/10 - craftsmanship and durable materials make it have good durability and strong practicality. - The rubber design is easy to maintain, save time and effort, and is not easy to damage. - Overall stable design, easy to use, easy to carry, storage will not take up too much space. - Suitable for correcting the bow holding posture during the practice of the violin instrument. - This bow straightener is a birthday gift for a friend who plays the violin. They will like it. Package list: 3 x Violin Posture Corrector