Go here http://www.ronlund.com/Merchant2/mer...y_Code=Filters
And scroll down to fuel magnet and bubbleless klunk. The Heli guys use both. I don't think you are supposed to let the fuel magnet get dry. (It needs to stay submersed in fuel). I'm not sure about the bubbleless clunk. There was a pretty good thread on them at Runryder. I havn't used one. But I'm just getting into helis, and thats where Iread about them.