Natural Rubber flip flops. Now with new sizing. Natural rubber sole. with eco friendly PVC strap, for softer more pliable wear. Also added new deeper tread grooves providing better slip resistance and shock absorbency.Our Popular Red Crab is back! Eco Friendly Natural Rubber Sourced from Thailand. Natural Rubber is sourced from the Pará rubber tree. It is an Eco friendly, natural, sustainable material. It is the LATEX, that drips from the bark of the tree.