T M Marine 90 Degree Cockpit Scupper Drain White 113650 1 Speaker Per Box high grade MDF front baffle for 31936 high grade MDF front baffle for ultimate structural rigidity and no flex constructionCNC miter and dado design and construction for the ultimate in an airtight precision fit of all parts which ensures a rattle and noise free environmentRecessed side panels increase structural integrity and eliminates unwanted flex and vibrationSpecially formulated aliphatic wood glue ensures an airtight seal between all MDF parts with a second application of glue around all internal joints after final assemblyPneumatic applied brad nails pull tight and hold MDF parts during the glue drying process and help assure a no leak • Built in high capacity 1 The overall diameter of the mounting flange is 3 9 16" The check ball contained inside the cockpit scupper drain is molded and then ground smooth and round to provide better sealing against reverse water flow that occurs when backing the boat