Sometime in the 1950's, Carter came out with an accessory for their glass bowl fuel filter; it was called a "Magnatrap". This was a small magnet that fit inside the fuel filter. Of course, the magnet would trap any rust particles coming through. When the magnet's color changed from grey to rust, it was time to clean.
This was a very useful device as at the time a lot of the old time filling stations had very rusty tanks.
Jon.
