1. For martin or other guitar which couldnt reach it with a regular hex wrench truss rod adjustment.2. Two way L-shape truss rod adjustment tool.3. Made of carbon steel, durable and highly wear-resistant.4. Set for most kinds of acoustic guitar, electric guitar and bass.5. For locking hexagonal screws on the bridge, adjusting the guitar neck.Weight: Approx. 42-66g / 1.5-2.3ozLength: Approx. 75+126mm / 3.0+5.0inDiameter: Approx. 4 or 5mm / 0.2inOptional Type: 4mm/5mmsize:70x120mmMaterial:Carbon steelcolour:BlackPackage Contents:1 x 4mm wrench1 x 5mm 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 allowed error is +/- 1-3cm.