I use 1/4" nylon tubing. I get it from GreaseWorks, but they are local so it's easy for me to stop in and pick up some. Here is link to what I get. I've got some on my work bench awaiting install in my 240. The new clear line is nice for seeing any air bubbles going through the system.

https://www.greaseworks.com/store/product_info.php?cPath=27_43_72&products_id=476&osCsid=gqr1t4u761lm6ho4nd35l38ks0

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