Only the horizontal bands are judged for the FB designation:
https://www.pcgs.com/news/what-are-...on-roosevelt
https://www.pcgs.com/news/what-are-...on-roosevelt
Quote:
In the case of the Roosevelt dime, this special grade-related designation is known as Full Bands, which refers to the horizontal twin bands found on the torch that alights the reverse of this popular coin.
In the case of the Roosevelt dime, this special grade-related designation is known as Full Bands, which refers to the horizontal twin bands found on the torch that alights the reverse of this popular coin.