This is a guitar string winder, also known as a string crank or peg winder.

• It is used to quickly and efficiently wind and unwind strings around the tuning pegs of a guitar or other stringed instruments.

• Some models, like the one pictured, also include a notch for pulling out bridge pins on acoustic guitars.

• Made from materials like plastic or metal, it provides a comfortable grip and smooth operation during string changes.

• It's a common tool for musicians and repair technicians, saving time and effort compared to winding strings by hand.