Function: 1. Built-in rotatable screen, reserve the most commonly used cords, best tool for finger placement practice. 2. Using steel guitar strings will add tension. You can adjust the number of strings for easy use. 3 The Metronome function allows you to learn code with your own personalized tempo 4. Lightweight and easy to carry and practice. 5. No noise or interference, convenient and practical. Specifications: Material: Metal + Plastic Color: Black Size: Approx. 11.4 x 2 x 1.6in Battery Model: CR2032(not included) Packing List: 1 x Cord Trainer 1 x Wrench 1 x Carrying Bag