I asked my brother, an engineer with a big math background. I said that sometimes clients prefer to combine 2 different overlays. At first I thought it might be 100, but he brought up the point that if it does not matter whether blue is on green as opposed to green on blue in that case the total would be 9+8+7+6+5+4+3+2+1, or 45 colors. This only refers to situations when two colors are used. This does not include instances when two overlays of the same color are chosen. That adds 10 more possibilities. There are 10 more possibilities when counting the usual single overlay. What do you think? Leave your comment below at the right.

See the available overlay colors at the www.irlen.com store. Click THIS LINK.