You’re going to want to look more for the heavier models based after the 111. With Juki and consew for leather. There are a prevalent amount of 31-15’s and models similar if we’re using singer as the basis. But that I believe the 31-15 model should be the starting point for 8 oz leather and down. If you’re looking for heavier than that always check Facebook marketplace or offer up. Then google the exact machine you are looking at. Model number not serial.