[frame]
It is the Owen Burton front antiroll bar, and also an Ital rear bar as well.
Also has negative camber eye bolts fitted and set to give ~1° negative. As a result probably around 5° caster that gives excellent turn-in and straight running stability, at the expense of slow speed heavier steering.
Both the eye bolt mounts and the front tie rod mounts have been strengthened, after showing early signs of stress.