These sleeves are used to install Vintage tuning keys onto modern 10mm tuner holes. (Usually vintage guitar tuner sleeves are 8mm in diameter)[High quality materials] 100% brand new and high quality. These guitar conversion sleeves are made of high-quality material, durable and long service life. [Application] guitar conversion sleeve is a common tool for guitar mechanic. It can be used to install Vintage tuning keys on modern 10mm tuner holes. [Good workmanship] the sleeve tuning wrench has a small body and has great performance. The excellent process of the product ensures the edge of smoothness and structure. [Product Specs] 12 x Guitar Tuner Converter Sleeves. The outer diameter is about 14.3mm. The inner diameter is about 10mm. Material: PlasticColor: Silver Package Contents:12 x Guitar Tuner Sleeves Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement error is +/- 1-3cm.