Chrome round flange with standard 3 screw hole pattern OEM fit.Removable inner chamber with no special tools required by using the tab end of the plug and unscrewing CCW and screwing CW to reinstall. Protective screen on each end of inner chamber. Our product is precision designed and manufactured using only the highest quality, non-corrosive materials for use in fresh and salt water applications. The patented one way internal check-valve design prevents water from entering the boat in the event one forgets to replace the plug. The design also allows for easy draining and cleaning. Truly a "must have'' for any boat. The drain plug's universal two and three hole design pattern makes the unit a direct replacement for the common style drain plug units used on most bass and ski boats and can be installed in minutes.