This black gasket is used for installation of rod holders instead of bedding with compound making it a convenient and easy installation. This will ensures a watertight seal when mounting a Flush Mount Rod Holder to your boat. The gasket material has a thickness of 1/16", length of 3-15/16" and width of 3-1/6". To match up your rod holders with this installation gasket match up the holes which the dimensions can found on the image above.