Medium (for most women’s and men’s shoes under size 9) Like all shoe bags, ours keep dirty shoes away from the rest of the clothes in your Knack. Like most shoe bags, ours have a drawstring closure to keep dirt from shoes in the bag. Additionally, our shoe bags have an interior divider wall that keeps the shoes from rubbing against each other when they are in the bag (so fine leathers aren’t scratched) Finally, in keeping with the expansion and compression functionality on almost all of Knack’s products, our shoe bags’ main point of difference is that they have a compression function to minimize the amount of space shoes take up in a Knack. Simply put the shoes in the bag in opposite directions (one shoe goes in toe first and the other shoe goes in heel first) and then cinch the two compression straps to minimize the space the shoes need in your bag (light compression for fine shoes or high heels and heavy compression for athletic shoes).