User blog comment:Draven, the Glorious Executioner/Seroch, the Mirror Nomad/@comment-7481207-20140418163319

"The mirror has a width of 1 pixel."

That mirror would be so thin that it would be nearly invisible. Also, measurements in LoL are made using ingame units. Even so, 1 unit is horribly little. The actual width of a wall (or mirror) matters very little unless its a wall like Anivia's W. In this case, the width only affects how easy it is to spot it.