|I was thinking I should wear some leather boots or something. In case of stray arrows, you know?|
— A mech wolf talking about the leather[src]
Leather was a piece of loot collected by Sly Cooper in the job "Shopping Spree" of Sly Cooper: Thieves in Time. It was taken from the shoemaker's. According to several Mech Wolves, leather was the best material to make arrow-proof boots out of. It was used, along with the Metal and Wood, by Bentley to create the Archer Costume for Sly.
The leather was a piece of a scrap tied up with a strip of leather.