Used 5-6 times in a nearby stream. Since it hasn't been used for canyoning or stream trekking, the felt sole shows only minor wear. The following is the product description from the manufacturer. For your reference. These sandals can be converted to felt soles, which are highly effective on moss and slippery surfaces, by using the separately sold Sawatabi. The soles can be attached simply by securing them with the straps. 【Material】Polypropylene, Felt 【Weight】137g (Size M, per foot) 【Color】Black (BK) 【Size】Compatible shoe size: L (26.0～27.0cm) *The compatible shoe size is based on Montbell's canyoning shoes. For shoes from other manufacturers, we recommend checking the fit in-store.