Secondary flare provides a marginal metal of:
10-20 degrees
30-40 degrees
140-150 degrees
None of the above
Secondary flare:
It is a flat plane superimposed peripherally to the primary flare. Advantages are:

Secondary flare ensures cavosurface margins to extend into embrasures (self-cleansing area).
Permits easy burnishing and finishing of the restoration.
Produces more obtuse-angled and stronger cavosurface margin.

In class II cast gold inlay, proximal box should have flares so as to have metal of 30-40° which is burnishable.