Review on K&N Universal Clamp-On Air Intake Filter: High Performance Premium, Washable, Replacement Filter, 4 In Flange Diameter, 5.5 In Filter Height, 1.125 In Flange Length: Round Tapered Filter, RG-1001BL by Brian Dildine

This is a genuine K&N air filter but I believe it is one of their cheaper filters. they are NOT sealed. You can remove the rubber boot from the filter (not only 2 inserts for different sizes, but also a 4 inch rubber boot containing the inserts). In my version, this provides a potential area for dirt and water ingress. Even when installed, you can rotate this filter around this boot. Other than that it's still tight and probably won't cause any problems. But be aware. A simple silicone roller around that seam solves that problem if you're concerned. Also, I just installed it and it seems like a great filter!