vision slit

vision slit

[′vizh·ən ‚slit]
(ordnance)
A narrow opening or slit in armor to permit viewing, especially one in a tank or other armored vehicle.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Like nukes, fuel-air explosives are unconfined explosives with long pulses, but the pressure is low, and if you are in a bunker or an armored vehicle, the pressure coming through the vision slits will be insufficient to collapse your lungs.