The metal shaft is made of hard steel, abrasion resistance.
Specifications: Material: Engineering plastics & Steel Inner bore size: Approx. 0.65cm / 0.26in Overall Length: Approx. 16cm / 6.3in Handle Length: Approx. 10.5cm / 4.13in Specially designed for tuning guzheng and most small machine devices that have quadrilateral openings.This item is the small wrench,perfect for piano. If you need a big one,please choose carefully.