There is no adhesive holding the lexan scales in place, but you can simply place cellophane tape over the point where your scales overlap. Not an issue.
The scales come in 16" lengths. They offer left-to-right and right-to left scales in ranges of 0-16, 16-32, 32-48, 48-64 and 64-80. Metric scales come in ranges 0-41, 40-82 and 81-123mm.
Keep in mind that you will need to consider the width of you guide rail when figuring the scale you will need -- you will be cutting off the portion of scale from 0 to about 8" or so depending on how the stop correspond... Hopefully Ron or Ryan will elaborate on this aspect, as I don't own their parallel guides and am not sure the exact amount that needs cut off to work with their product.