The Neptune 108102 is an O-ring gasket designed for use with Neptune's 4-inch cap models, including the VTF, DBF, and FTF feeders. Its dimensions are 3.61 inches in inner diameter, 4 inches in outer diameter, and 0.203 inches in thickness. This O-ring ensures a secure seal, preventing leaks and maintaining optimal performance of the feeders. It's compatible with various Neptune feeder models, such as: VTF-2HP VTF-5HP VTF-10HP DBF-2HP DBF-5HP DBF-10HP FTF-2HP FTF-5HP