UK sizing One extra benefit of membrane-free shoes is that leather can be used as a liner material. This is great in terms of how well the shoes conform to your feet over time: the Bangri shoes settle in perfectly as you keep wearing them. The Bangri is classified as an AB class shoe, making it perfect for when you want light support for your ankle but are not carrying a heavy backpack. - Surface made of yak leather - Leather liner - Vibram Endurance Pro sole - Tip and heel with light rock protection