Got another question. I'm using the European 16mm OD/ 10mm ID tubing (DD/Feser 3/8 in). When using the included 3/8 x 5/8in. fittings, I noticed that if I try, I can pull the tubing off the fitting even after screwing the compression all the way down. This is actually physically pulling on the tubing using medium force. Do you think I run the risk of the tubing popping off the fitting using these? I ask because this does not happen when using metal 16/10 fittings.