Colour-switching ink are available around the obverse aspect from the bill in two distinctive places- on the freedom bell and over the numeral "100" Situated over the lower proper corner. Check out this site For more info and instruction resources on authenticating present and older types of U.S. currency. The https://knoxjueov.blogofoto.com/65076047/5-simple-statements-about-counterfeiting-money-in-the-usa-explained