Martin Style Truss Rods

[B. Howard]

that is the old 1 way rod Martin is now using the 2 way adjustable. this is 1/4 in wide with a 3/8 wide lower end at the barrel nut.

What is the difference between a one way and two way, can it be used at both ends ?

J

A one way rod can only pull back against string tension to remove excess relief. A two way rod can also add relief to the neck if the strings do not pull enough on the neck to suit certain players and styles. From a set up standpoint adding relief is rare but it is always nice to have the option in those instances when you need it. As long as clear access to the adjustment is created there is no reason these rods cannot be used with the adjustment at either end.