This cone-shaped air filter from K&N is designed to work in the Swift Sports 2000 racecar air scoop, but it can be adapted to a wide variety of custom applications. The large inlet end is flexible enough to conform to an oval or rounded rectangle. The small end has a hole to allow debris to pass through the scoop.
Inlet: 5.75" Outside Diameter / 18" Circumference
Small End: 2" Outside Diameter
Effective Filtering Area: 202 square inches (enough for a 410 CID V8 revving to 10,000 rpm!)