You can get one from Thomann. Martin acoustic guitars and some others will place the truss rod adjustment access nut inside the soundhole at the base of the neck. In this case you'll just need the ...

15mm), acoustic and bass guitar (.008 ... For the wheel type of truss rod adjustment at the base of the neck that I mentioned earlier, while looking from the bottom of the guitar body, rotate ...

Furch Guitars has just unveiled a piece of acoustic guitar engineering that could put your local tech out of business ... “This movement is then transferred to automatically adjust the neck angle, ...