Strong aluminum one-way truss rod, similar to the design used by Martin for many years.
The aluminum U-channel has an internal 3/16" steel rod, and a 5mm allen adjusting nut with washer.
M6 x 1.0 thread
Width: 0.472" (12mm)
Depth: 0.400" (10.16mm)
#1177 Acoustic: Designed as a soundhole accessible truss rod, and is the same as installed in Martin guitars made after 2007.
#1177-E Electric: For peghead or heel adjustment. This style of rod is found in many production guitars, and is also preferred by many custom builders because of its simple design and strength.
#1177-B Bass: For control of beefy bass necks. Can be installed for peghead or heel adjustment.