The Cranmer abacus has a plastic frame with 13 metal rods each of which has beads that are moveable. There is red felt behind the beads that keeps them in place when they are moved on the rods. A horizontal bar divides the top bead in each rod from the 4 beads below the bar. Take an abacus and gently shake it up and down and you can observe that the beads do not move from their original position.
The photo below shows the name of each column. Note that at every third column as you move from right to left there is a raised line called a period. Think of this as a comma. The periods divide the abacus into the hundreds, thousands, millions, and billions as shown in the photo.
Beads above the bar have a value of "5" while beads below the bar have a value of "1." The photo below shows the value of each specific bead on the abacus. From the far right the bead above the bar is valued at "5" while each bead below the bar is valued at "1." Moving to the seventh column from the right, the millions column, the bead above the bar is valued at 5,000,000 while each bead below the bar is valued at 1,000,000.