These penny sleeves are for 63.5 X 88 MM Card sizes. What is a penny sleeve? Originally, they would have been sold as $1 per pack for 100 sleeves, or $0.01 per sleeve, hence "penny sleeves". These are thinner than typical sleeves at just 50 microns but still 25% thicker than most other penny sleeves that come in at 30 - 40 microns.
Thicker Than Any Other "Penny" Sleeves - Most "Penny" Sleeves are 30-40 microns thick. These are 50-microns thick! That is 25% thicker than most!
These are sized to fit cards Card Game Card Sleeves (63.5x88 mm).