A pair of roller style retainersThe rollers on them can lessen the stress on your strings, which allows the guitar to stay in tune longerThey also can prevent wear and tear on the strings, which results in longer string lifeCompatible with electric guitar and 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. to look great on your guitar Base Size (L x W): Approx. 043 x 023 inch / 11 x 6mm Height: Approx. 047 inch / 12mm (including the roller)Roller Size (L x D): Approx. 04 x 02 inch / 10 x 5mmString Spread (Center to Center): Approx. 027 inch / 7mmMaterial: Zinc alloyColor: ChromePackage Contents:1 pair of retainers2 x Mounting screwsOnly the above package contents are included, no other products are included.Note: Light and different displays may cause the item color in the picture to be slightly different from the real color. Measurement tolerance is +/- 1-3cm.