Chaco Men's Z1 Classic Sandals Split Grey Outsiders Store UK Chaco Chillos Women's Sport Sandals Aqua Gray Outsiders Store UK Chaco Men's Z1 Classic Sandals Shear Navy Outsiders Store UK Chaco Men's Z1 Classic Sandals Sierra Black Outsiders Store UK. History has it that when Mark Paigen designed and made the first Chaco sandal, a French friend described it as Zee One and so that style became the Z 1. That sandal became an icon, renowned for its durability and comfort, ensuring it a dedicated following. With a reassuring weight, this sandal is deserving of its title as an original, whilst being extremely comfortable; developed to support your feet on any terrain. Here at Outsiders, weve never worn a more comfortable sandal, I suppose you could count us amongst the converted.