Yes these are "Standard" size card sleeves. They are specifically designed to fit 63.5 X 88 MM cards but the external dimensions of the sleeves are commonly referred to at 66x91 MM. It doesn't make any sense why these are the only cards referred to by both their internal and external dimensions but if you're looking for sleeves that are 66 x 91 MM, you've come to the right place. These are the most common sleeve size BY FAR in the industry, the MTG sized sleeves.

Expertly engineered to fit all of your favorite games with cards sized 63.5x88mm!

Popular for use with:
A Game of Thrones LCG™
Dominant Species™
Race for the Galaxy™
Eaten by Zombies!™
Call of Cthulhu LCG™
Pandemic™
UFS™

If you do not know which sleeves fit your games, visit the following page, type the game you are interested in the search bar and you will find the sleeves results that are suitable for it: www.sleeveyourgames.com