They're hollow.
I've got another set on order already but thought I'd try crashing one more time with the current ones.
I like the fact that these ones (aside from looking the best...) are far enough away from bodywork that when they do get bent no metal touches plastic. Would other bars have fared better in my particular crash at the speed I was going and on the same rutted dirt road...perhaps but probably not.
Still cheaper than new plastics.
and they look the best.