The Top Lok II is a type of string locking mechanism designed for Ibanez and installed on some Ibanez guitars.
The Top-Lok II is used to lock the string behind the nut. This design allows the guitar to maintain tune when the tremolo is used by reducing the length of the string which is stretched.
The drawback of a locking nut is that the nut must be loosened with an hex wrench if the player needs to tune beyond the range of the fine tuners on the bridge.
The Top Lok II differs from its predecessor the Top Lok in that all three locking pads are aligned in a single plane. This makes it similar in appearance to the Top Lok III and allows for use with an angled headstock. It was used on a couple of Artist series models, the solid body AR350 and the hollow body AM75, as well as a small number of Destroyer models.
These behind-the-nut designs were supplanted by the Top Lok III, which was introduced in 1986 along with the Edge tremolo. The Top Lok III integrates the function of the nut with the string locking mechanism, thus eliminating the friction and wear caused by the string sliding through the nut slot.