RPF1 center cap weight

[Yarflana]

See here to ensure you know what I am referring to:
http://store.enkei.com/product/enkei-rpf1-cap

Does anyone know the weight of a cap? They are aluminum so they cannot add that much more weight, but I am curious because since the point of buying the RPF1s, at 13.7 pounds for 16x7s, is obviously to reduce weight. If they are more than 1/2 pound a piece, I will not plan to get them.

However, my only question is whether for acceleration, they shouldn't affect things much since they are not adding weight to the outer diameter of the wheel, but only at the center, so they are more of a static weight, vs. a kinetic weight (I know there are better terms for this, but I think you racing folks know what I mean).

Thoughts?

Thanks,
Pat