Rub washers are small washers that sit underneath the head of the bolts or lags to keep a space in between the base of the fastener head and the wood or stone it is installed against. These hidden washers prevent the swirl marks that can happen when installing the nuts, bolts, lags and screws. Our rub washers are only available in a black finish and come in the following sizes, 1/4", 5/16", 3/8", 1/2", 5/8", 3/4", 7/8" an 1".