The PC Racing reusable oil filter. I had one on my BMW first and have pretty much used one since. Now it's on the Sportster.
To service it: take it apart and pull the filter element. Find somebody with an ultrasonic cleaner and clean it. Let it dry or use compressed air. Put it back together and slide it back in.
The pitch is saving money and the environment, since you're not throwing away a filter every change.
