The truss rod wrench is made of quality metal Long handle length allows easier access to truss rod cavity Fits most (Not All) guitars as well as other guitars needed wrench Features nut driver on one end and a handy screwdriver at the other Used for tweaking the amount of relief in the neck, suitable for electric guitar replacement parts The 6.35MM (1/4 inch) model is suitable for most folk guitar series, ( to the 's classical guitar) (please pay attention to the size data of the long and short models, if you buy the long model, the length may cause the length to stand against the wood. Cannot be inserted into the hole, buying a short one and buying a long one may cause the length to be not enough to be screwed into position) The 7MM model is suitable for some Korean , , and guitars. Please choose according to the actual size of your own piano (please pay attention to the length and short size data) The 8MM (5/16 inch) model is suitable for some American-made electric guitars and ESP electric guitars. Please choose according to the actual size of your own piano (please pay attention to the length and short size data) Colour: Silver Material: iron Size: 7MM/8MM/6.35MM Package Contents: 3 x Guitar Truss Rod Wrench Only the above package content, other products are not included. Note: Light 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.