The commandment of chalitzah is [performed before] three judges, even if all three are laymen.  [If] she performed chalitzah with a [leather] shoe, her chalitzah is valid; with a cloth shoe, it is not valid; with a heeled sandal, it is valid; with an unheeled sandal, it is not valid; below the knee, her chalitzah is valid; above the knee, her chalitzah is not valid.