Chaco Flip EcoTread Flip-Flops (For Women) If foot-slapping sandals make you flip out, lose the "flop" through the ingenuity of Chaco's Flip EcoTread thong sandals, which remove the flopping effect by seating the upper straps back under the midfoot of the anatomical LUVSEAT footbed. Fixed nylon straps anchor under midfoot to eliminate "flop" LUVSEAT anatomic footbed provides arch support EcoTread outsole is made from 25% recycled rubber EUC mostly worn indoors..