Guitar Repair Hex Wrench Guitar Set of 3: 6.35mm, 7mm, and 8mm The 6.35mm (1/4") model fits most Taylor acoustic guitar series (does not fit Taylor classical guitars). The 7mm model fits some Korean-made PRS, Japanese-made Jackson, Taylor, and Ibanez guitars. The 8mm (5/16") model fits some American-made Gibson electric guitars and some Japanese-made ESP electric guitars. Note: Each model has a screwdriver set on the tip. The screwdriver port can be fixed with a 5mm thick screwdriver.