This is what I use
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1/2" ID Silicone Tubing, Food Grade 1/2" ID x 5/8" OD 10 Feet Length Pure Silicone Hoses High Temp for Home Brewing Winemaking
Depends on what your using it for. But I would definitely NOT use any aluminum. Copper or stainless is best if your plumbing it but if it's just to fill with silicone hose is fine.
While the product description doesn't mention anything about the durability of the thermometer, customers do seem to have opinions on it. I did not find any reviews mentioning the durability of the thermometer.
If I remove the filter. Can I use this for heating a sauce and other condiments that might contains spices and small grains of chile seeds? Without the filter can the sauce flow freely through the valve?