5 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 10 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 10 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): . 0.43 x 0.23 inch / 11 x 6mm Total Height: . 0.47 inch / 12mm (including the roller) Roller Size (L x D): . 0.4 x 0.2 inch / 10 x 5mm String Spread (Center to Center): . 0.27 inch / 7mm Material: Zinc alloy Color: Chrome Package Contents: 5 pair of guitar string retainers 10 x Mounting screws Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.