Sei headless basses - put a capo on fret 1 (or where it would be on the fretless), hold string down and check height, twiddle allen key in truss rod end conveniently located at end of neck until height is right. They have something of a mind of their own as to whether to move or not, so I'm ready to adjust them any time. The Flamboyant has been getting used and hasn't shown any sign of moving in the heat.