Here is some info about them ask me anything! Our #1 best-selling adventure sandal, the Circadian features a medium-thick 9mm Vibram® sole, excellent wet grip, and a moderate ground feel. Thickness: 7.5mm outsole + 1.5mm footbed = 9mm Sole: Vibram Gumlite Outsole (Domestically Sourced) Footbed: Earth Grip (Moisture-wicking Canvas, GOTS (Organic) Certified Small Batch Dye) Our sandals are designed to keep you grounded via Grounded Conductive Laces™. When worn on bare earth, Earth Runners give you an effective connection with the ground, through a copper lace plug on the outsole. Electron transfer between your body and the earth is facilitated through the stainless-steel lined lace circuit. This process grounds the body via intimate connection of lace and foot–similar to that of being barefoot.