Sweetwater heater coil. If its safe enough for the fishies, i guess its safe enough for me

I may use that in a spare tire tank and have the tips stick through the top of the tank. Is it 8" tall? Also, i wonder if there is a filter that would fit in it?, Maybe a VW A2 or A3 one?

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius