:I "Finally"got curious to figure out what this means? So my brief answer I found to the question is... JAN tubes are Joint Army Navy tubes that were manufactured for the military,and were manufactured to military specs.Just thought I'd share this with any others interested to know.Mike L.
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If you run across a tube that has a suffix "AL" that means "AirLine" and is supposed to be the highest quality tube you can get.
Lewis