One-Way Shields are a different way for zombies to get into the map, besides the standard Barrier, introduced in Magma-Man's map, Lockdown. These are placed instead of walls in certain parts of the map, and let things on the outside of the map get in but don't allow things on the inside to get out. It also does not let bullets or other projectiles through, so usually a window is placed beside the shields so players can shoot at the zombies before they get into the map.
In Lethal Lockdown, the players can shoot through the shield. They are almost identical to normal barriers but cannot be repaired until they are completely broken. Repair time is about four seconds, two if using Timeslip.
