Take a look down at your canvas sneakers (you do have some, right?), and turn your foot just a little bit to the side. That rubber sidewall running along both the upper and the sole is the foxing. And while it serves a decorative purpose—just check the stripe in the picture above– or the “sea worthy” line on any pair of plimsolls—it’s also a crucial structural component of classic, vulcanized rubber kicks. Though the sole of your Authentics is glued to the insole and upper with industrial strength adhesive, that adhesive is prone to degradation, and eventually it’ll start to give way. Short story: with a bit of time, the sole of your shoe is going to want to fall off. The foxing is an added layer of defense in keeping this from happening. It’s glued to the upper and the sole so the upper has two points of connection, and it’s also subjected to heat and pressure that strengthens the bond between the foxing and the sole. All this makes for a more durable piece of footwear. So next time you’re out for a walk, enjoying the feeling of not having a slab of shoe rubber flapping precariously off the bottom of your foot, thank foxing.