"Never saw the source they were using, but I can tell you it packs one hell of a punch when they zap you with it. Kind of like what being hit by lightning must feel like, I figure."

Bucky nods at the thing in Steve's hand.

"Not that one exactly. They were using the same whatever-it-is in some of the stuff they had in... where you found me."

A beat, and he adds,

"Dialed back more than the stuff in the guns and tanks, though. Which is probably good. Else I'd be glowing in the dark."