I wondered this myself... I tried googling it but nothing came up. All I know is that the leather is incredible, incredibly buttery soft that gets better and better with age. It is also thick and durable and water-resistant. It might not be scratch-resistant (unless you buy a bag that’s made of pebbled, glove-tan leather), though but other TPFers feel free to correct me.
I highly recommend you check out the entire 1941 line, as the bags in this collection are entirely made of this beautiful leather and it’s amazing. Once you feel this leather in your hands you never want to go back. It’s so... so... so soft.