Printing. US bills have raised printing, and all lines needs to be sharp. Seek out irregularities in definition among bills along with traces wavering in thickness, color or clarity. One particular is found on The underside still left of President Lincoln’s portrait and another is higher than the Treasury seal https://onelifesocial.com/story2164400/considerations-to-know-about-how-to-tell-if-bills-are-counterfeit