First, they fitted the Signature South 40 with a new low profile Vibram 360 Force sole that provides better balance, stability and ground feel. They replaced the original outside molded sole with a heavy duty 6-1/2 oz. bullhide leather. And to make long days afield chasing birds behind spirited dogs a joy, They built in a heavy duty Poron Technical foam layer between the molded sole and the vamps, (does not compress with wear)! Poron underfoot softens up the walk considerably, a feature you will enjoy at the end of a long day. The South 40 features double vamp construction made from waterproof WeatherTuff Leather, fully leather lined with soft Agua Tan waterproof leather, standard quick lacing studs…and made by hand to your exact measurements. Lightweight and nimble for all day comfort. Your dog will think you’re on steroids!