The 4mm and 5mm neck tension rod of the guitar key with ball tip are elongated, ideal for narrow or deep lattice rod likes Martin guitar adjustments. Gauge: 1.5mm, 2.0mm, 2.5mm, 3.0mm, 4.0mm, 5.0mm, 1/20in, 1/8in, 3/16in. The guitar hex key set is made of carbon steel, durable and highly wear-resistant. Various gauges suitable for most guitar screw adjustments. For locking hex bolts on the bridge, adjusting the guitar neck. The 6.35MM (1/4 inch) Pipe Wrench model is suitable for most Taylor folk guitar series, (not suitable for classic guitars of this brand)The 7MM Pipe Wrench model is suitable for some Korean PRS, Nissan Jackson, Taylor and Nissan Ibanez guitars. Please choose according to the actual size of the piano8MM (5/16 inch) tube wrench model is suitable for some American Gibson electric guitars and Nissan ESP electric guitarsOlor: BlackMaterial: MetalPackage Contents:1x4mm Ball Wrench1x5mm Ball Wrench9 x Wrench Set3 x Pipe WrenchOnly 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.