This insert helps to ensure
"This insert helps to ensure the connection of the dip tube to the liquid outlet post is more secure. It still remains a bit tricky getting the insert aligned in the centre so as the barb of the liquid post can enter the opening of the insert. Likewise the fit of the dip tube and the insert opening is a tight one and use of a food grade lubricant helps. It seems a much better option to the small silicone elbow that was also troublesome to fit."