When Mechanical boards ruled the earth, space bars were big and strong, they were the kings and queens of any layout; while they were very long ones, one particular size, the 7u ruled over most of the others. Minor species came after, more due to the trade off imposed by a particular key that forced her way into most keyboards, the windows key. However, there are still classic keyboard, that has not been affected by that windows illness, and that still show 7u's proudly. It even went into a very few and special 60 layouts. Sadly, it seems to be an endangered species of space bars, the weaker 6.25u's, victims of the window key, are surviving.
