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.