twenty steel frames

Light erupted from Misaka Mikoto’s fingertips.
Her coin was launched at three times the speed of sound, easily slicing through the thick
steel frames supporting the building. The men with the guns took a blast from the slight
fragments, swept away just like that as the esper who’d been aiming at Mikoto’s head
from an upper story lost his footing on the crumbling supports and was swallowed down
into it. The single railgun had crushed through almost twenty steel frames, finally
coming to a stop after inflicting cracks on the wall of a different building.

- Toaru Majutsu no Index Volume 8, Chapter 3 Part 3