2 Pcs Guitar Wrench, Black 4mm Ball Head, Silver 5mm Ball Head, Length 125mm, Width 75mm, Metal Wrench Tool, Guitar Allen Wrench, for Martin Acoustic Guitar, Guitar Truss Rod Adjustment

Well designed for awkward-to-get-to hex sockets and enable decent leverage. I bought these for adjusting guitar neck truss rods. Seem well made enough, nice to have a different colour finish for each size. Recommended!

Fitted the slot well enough. Truss rod rather difficult to turn though so it's only had a quarter turn as I don't want to force it and risk breaking it. Letting it settle now and hoping it'll be enough