Originally Posted By: ZeeOSix
If done right, non-metal end caps - or no end caps at all - works just fine.
I like the Denso design best of any filter, simple and smartly engineered, no end caps, simple parts throughout. Fiber end caps can be better than metal, as they don't waste metal and being more porous, the glue should stick better. But then the Fram U has metal end caps, I guess because of the wire mesh. The steel end cap with potting glue methid will eventually go away in favor of the no end caps design I would bet, because it is just more economical to make and works as well or better.