3-1/2" to 4" I.D. External FlapperPart Number: 810-EG-400
3-1/2" to 4" I.D. External Flapper
These are excellent American-made flaps that will not curl like cheap import copies. These are a must for boats with a very close distance between exhaust ports and the water line Clamp is included. This flap has a 4" ID and must be cut down for 3-1/2" applications. Sold each.