A pair of roller style guitar string retainers The rollers on them can lessen the stress on your strings, which allows the guitar to stay in tune longer They also can prevent wear and tear on the strings, which results in longer string life Compatible with electric guitar and bass This is a set of 2 chrome roller string trees. These string retainers are the type with the little rollers on them to help stay in tune and help prevent strings from breaking. They come with 2 mounting screws as well. Great replacement for your broken, dirty or old string retainer. Sure to look great on your guitar! Base Size (L x W): Approx. 0.43 x 0.23 inch / 11 x 6mm Total Height: Approx. 0.47 inch / 12mm (including the roller) Roller Size (L x D): Approx. 0.4 x 0.2 inch / 10 x 5mm String Spread (Center to Center): Approx. 0.27 inch / 7mm Material: Zinc alloy Color: Chrome Package Contents: 1 pair of guitar string retainers 2 x Mounting screws Only the above package contents are included, no other products are included. Note: Light reflection and different displays may cause the item color in the picture to be slightly different from the real color. Measurement tolerance is +/- 1-3cm.